This document describes a circuit design that can generate variable frequency and duty cycle output signals. It uses a crystal oscillator followed by counters and multiplexers to select different divisions of the oscillator frequency. The frequency and duty cycle can be independently controlled. Test results showed the circuit can clearly produce telephone speech through a small speaker.
This document describes the design and performance of two low noise amplifiers using the ATF-55143 PHEMT for 5GHz wireless standards. Both amplifiers provide over 10dB of gain and a noise figure below 1.5dB across their bandwidth. The first operates from 5.125-5.325GHz with an output IP3 of 26.5dBm and the second from 5.725-5.825GHz with an output IP3 of 26dBm. Circuit simulations and measurements of prototypes verified the designs meet specifications.
Design of a Low Noise Amplifier using 0.18μm CMOS technologytheijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
This document describes a project to generate sinusoidal pulse width modulated (SPWM) signals using a microcontroller. It discusses SPWM signal generation by comparing a modulating sine wave with a triangular carrier wave. It also describes implementing SPWM signal generation algorithms using an 8051 microcontroller and simulating the output in Proteus. The document further discusses designing half bridge and full bridge inverters using an IR2110 driver circuit and optocouplers to interface with the microcontroller outputs. Assembly code is also presented for generating a single phase unipolar SPWM signal with the 8051 microcontroller.
A Plasma Tweeter is an audio device which uses a pair of electrodes as a source of sound. It has a clear reproduction and Omni directional radiation pattern. A plasma tweeter has a better frequency response than a conventional speaker and does not involve any moving part (diaphragm) and thus has less reverberation and no wear and tear. Plasma tweeters invented earlier were very expensive. This paper presents a plasma audio system which is making the regular audio system more efficient because of the use of the latest plasma tweeter. Here the objective is to create a low cost and more efficient version of the most speakers invented till now with the complete audio system.
The document provides assembly and use instructions for the RelaiXed, a high-end pre-amplifier designed for balanced audio connections. Key features include a 64-step relay-based volume attenuator, infrared remote control, and separate power supplies per audio channel. Assembly requires carefully sourcing quality components like gold-plated PCBs, LM4562 op-amps, and Dale RN60-series resistors to achieve the best sound quality.
This document summarizes a 175μW 100MHz-2GHz inductorless receiver front-end in 65nm CMOS. It achieves over 17dB of gain from 100MHz to 2000MHz while consuming only 175μW from a 0.9V supply. The noise figure is 11dB and third-order intercept point is -16.8dBm. It uses a completely inductorless topology with a real input impedance of 300Ω achieved through current feedback in two stages, with a common gate stage at the input and common drain stage providing feedback current. The active area is just 0.017mm2, excluding pads.
Design and Simulation of Low Noise Amplifiers at 180nm and 90nm TechnologiesIJERA Editor
This document describes the design and simulation of low noise amplifiers (LNAs) at 180nm and 90nm technologies. The author presents the design methodology and calculations for component values. Simulations show the LNA at 180nm has a peak frequency of 1.04502GHz and noise figure of 259.722mdB, while the 90nm LNA peaks at 1.157GHz with a noise figure of 183.21mdB. Overall, the 90nm technology performs better with a lower noise figure. The author concludes smaller feature sizes allow for lower noise performance but further optimization is still possible.
Implementation of Simple Wireless NetworkNiko Simon
End of course project where students were given free rein to explore wireless concepts through analysis of theory and hardware builds. The transmitter sends a Morse code audio signal which is then outputted by the receiver. Test of Morse code output: https://youtu.be/-06qOH7lYCg
This document describes the design and performance of two low noise amplifiers using the ATF-55143 PHEMT for 5GHz wireless standards. Both amplifiers provide over 10dB of gain and a noise figure below 1.5dB across their bandwidth. The first operates from 5.125-5.325GHz with an output IP3 of 26.5dBm and the second from 5.725-5.825GHz with an output IP3 of 26dBm. Circuit simulations and measurements of prototypes verified the designs meet specifications.
Design of a Low Noise Amplifier using 0.18μm CMOS technologytheijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
This document describes a project to generate sinusoidal pulse width modulated (SPWM) signals using a microcontroller. It discusses SPWM signal generation by comparing a modulating sine wave with a triangular carrier wave. It also describes implementing SPWM signal generation algorithms using an 8051 microcontroller and simulating the output in Proteus. The document further discusses designing half bridge and full bridge inverters using an IR2110 driver circuit and optocouplers to interface with the microcontroller outputs. Assembly code is also presented for generating a single phase unipolar SPWM signal with the 8051 microcontroller.
A Plasma Tweeter is an audio device which uses a pair of electrodes as a source of sound. It has a clear reproduction and Omni directional radiation pattern. A plasma tweeter has a better frequency response than a conventional speaker and does not involve any moving part (diaphragm) and thus has less reverberation and no wear and tear. Plasma tweeters invented earlier were very expensive. This paper presents a plasma audio system which is making the regular audio system more efficient because of the use of the latest plasma tweeter. Here the objective is to create a low cost and more efficient version of the most speakers invented till now with the complete audio system.
The document provides assembly and use instructions for the RelaiXed, a high-end pre-amplifier designed for balanced audio connections. Key features include a 64-step relay-based volume attenuator, infrared remote control, and separate power supplies per audio channel. Assembly requires carefully sourcing quality components like gold-plated PCBs, LM4562 op-amps, and Dale RN60-series resistors to achieve the best sound quality.
This document summarizes a 175μW 100MHz-2GHz inductorless receiver front-end in 65nm CMOS. It achieves over 17dB of gain from 100MHz to 2000MHz while consuming only 175μW from a 0.9V supply. The noise figure is 11dB and third-order intercept point is -16.8dBm. It uses a completely inductorless topology with a real input impedance of 300Ω achieved through current feedback in two stages, with a common gate stage at the input and common drain stage providing feedback current. The active area is just 0.017mm2, excluding pads.
Design and Simulation of Low Noise Amplifiers at 180nm and 90nm TechnologiesIJERA Editor
This document describes the design and simulation of low noise amplifiers (LNAs) at 180nm and 90nm technologies. The author presents the design methodology and calculations for component values. Simulations show the LNA at 180nm has a peak frequency of 1.04502GHz and noise figure of 259.722mdB, while the 90nm LNA peaks at 1.157GHz with a noise figure of 183.21mdB. Overall, the 90nm technology performs better with a lower noise figure. The author concludes smaller feature sizes allow for lower noise performance but further optimization is still possible.
Implementation of Simple Wireless NetworkNiko Simon
End of course project where students were given free rein to explore wireless concepts through analysis of theory and hardware builds. The transmitter sends a Morse code audio signal which is then outputted by the receiver. Test of Morse code output: https://youtu.be/-06qOH7lYCg
This document describes the design of a low noise amplifier (LNA) for wireless applications operating at 900 MHz. The LNA was implemented using a 0.13um RF CMOS technology and a cascode topology with inductive source degeneration. Simulation results showed the LNA has a gain of 26 dB, noise figure of 1.04 dB, input return loss of -14 dB, output return loss of -6.55 dB, reverse isolation of -39.76 dB, and power consumption of 115uW from a 2.5V supply. The LNA meets the requirements of low noise figure, high gain and low power consumption for a 900 MHz wireless application.
The Franklin oscillator circuit uses two FETs instead of vacuum tubes and provides a local oscillator signal of about 700mVpp for a balanced modulator generating single or double sideband amplitude modulated waves. It can be built in a screened box using common components like a ceramic coil former from an electric heater element, a double bearing tuning capacitor of 20pf, and a 5pf trimmer capacitor. With the addition of an LO amplifier and low pass filter, this Franklin oscillator design can generate a DSB/SSB signal for transmission on amateur radio bands like 80 meters.
IOSR journal of VLSI and Signal Processing (IOSRJVSP) is an open access journal that publishes articles which contribute new results in all areas of VLSI Design & Signal Processing. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced VLSI Design & Signal Processing concepts and establishing new collaborations in these areas.
Equal Split Wilkinson Power Divider - Project PresentationBhanwar Singh Meena
This document discusses power dividers and describes the design of an equal-split Wilkinson power divider. It explains that a power divider splits an input power signal into two or more output signals of lower power. A Wilkinson power divider uses quarter wave transformers to split power in a 3dB ratio. The document then provides specifications for designing a Wilkinson power divider to operate at 2.4GHz using a substrate with permittivity of 3.38 and thickness of 1.524mm. It calculates the impedance values needed for the divider and uses a circuit design tool to calculate the microstrip line lengths and widths.
Directional couplers ppt for microwave engineeringDivya Shree
Directional couplers are passive microwave devices that divide power and distribute it through multiple ports. They have four ports: input, through, coupled, and isolated. Power entering the input port splits between the through and coupled ports, with some power coupled out through the coupled port. Directional couplers are characterized by their coupling factor, directivity, and isolation factor. They are used in applications such as power monitoring, signal sampling, and reflection coefficient measurements.
A low dropout (LDO) voltage regulator with high power supply rejection ratio (PSRR) and low
temperature coefficient (TC) is presented in this paper. Large 1μF off-chip load capacitor is used to
achieve the high PSRR. However, this decreases the gain and pushes the LDO’s output pole to lower
frequency causing the circuit to become unstable. The proposed LDO uses rail-to-rail folded cascode
amplifier to compensate the gain and stability problems. 2nd order curvature characteristic is used in
bandgap voltage reference circuit that is applied at the input of the amplifier to minimize the TC.
The characteristic is achieved by implementing MOSFET transistors operate in weak and strong
inversions. The LDO is designed using 0.18 μm CMOS technology and achieves a constant 1.8 V output
voltage for input voltages from 3.2 V to 5 V and load current up to a 128mA at temperature between -40 °C
to 125 °C. The proposed LDO is targeted for RF application which has stringent requirement on noise
rejection over a broad range of frequency.
A directional coupler is a passive device that couples part of the transmission power from one transmission line to another. It has four ports: input, transmitted, coupled, and isolated. Key parameters are coupling factor, loss, isolation, and directivity. Directional couplers are commonly used to monitor power and frequency without interrupting the main signal, for frequency and power measurements, and combining signals to a receiver when isolation is high.
A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency. It was long believed to have been invented by US engineer Edwin Armstrong,
A high efficiency BPSK receiver for short range wireless networkTELKOMNIKA JOURNAL
1) The document describes a high efficiency BPSK receiver for short range wireless networks designed and simulated in 0.18 μm RFCMOS technology.
2) The receiver uses injection-locking techniques with a Colpitts oscillator to improve efficiency. It has a DC power of 0.474 mW and sensitivity of -60 dBm.
3) Simulation results show the receiver's oscillator has a phase noise of -160 dBc/Hz while consuming 0.377 mA from a 0.7 V power supply. The receiver can achieve a data rate of 5 Mbps with a figure of merit of 94 pJ/bit.
This document describes the design of a 16-channel audio mixer. It begins with an introduction to audio mixers and their uses. It then discusses the design methodology, considering factors like the number of input/output channels, power requirements, cost, and portability. The design is divided into several stages: a power stage using a step-down transformer and rectification circuit, a stereo stage for each channel with gain, bass, and treble controls, an auxiliary stage to boost the output signal, and a volume control stage to jointly control the levels. Block diagrams and circuit diagrams are provided to illustrate the design. In conclusion, the 16-channel audio mixer is tested by connecting it to an external amplifier and speakers.
This document describes the design of a lock-in amplifier micro-ohmmeter using Proteus VSM simulation software. It discusses the design in four stages: 1) the source stage containing an excitation oscillator, frequency divider and attenuator, 2) an instrumentation amplifier stage, 3) a filter stage, and 4) an output stage with a voltage controlled oscillator. Mathematical equations are provided for the components in each stage. The design of each stage is analyzed at the component level and verified through Proteus simulation. The simulation results matched the theoretical operation, confirming the successful design of the circuit using Proteus.
This document describes the design of an equal split Wilkinson power divider with the following specifications: frequency of 2.4 GHz, source and load impedances of 50 ohms, substrate permittivity of 3.38, substrate thickness of 1.524 mm, and conductor thickness of 0.15 mm. It provides background on Wilkinson power dividers, describes the calculation of microstrip line widths and lengths, shows the simulated circuit schematic and layout, and plots the resulting S-parameters which achieve the desired 3 dB power split with good port matching and isolation as expected.
Design of Ota-C Filter for Biomedical ApplicationsIOSR Journals
This document describes the design of an OTA-C filter for biomedical applications such as ECG signals. A fifth-order low pass Chebyshev filter with a cutoff frequency of 300Hz and power dissipation of 779nW was designed using a 0.18um CMOS process. Simulation results showed a gain of 22.5dB and CMRR of 93dB. The fully differential OTA-C filter provides higher common mode rejection and dynamic range compared to single-ended designs, while operating transistors in the sub-threshold region reduces power consumption. The proposed filter is suitable for low power portable biomedical applications.
Design of Low Noise Amplifier for Wimax ApplicationIOSR Journals
The document describes the design of a low noise amplifier (LNA) for WiMAX applications operating in the 3.3-3.8 GHz range. It discusses testing the transistor to check for stability and gain. Input and output matching is performed using stub matching networks to achieve low noise figure and high gain. A passive biasing circuit is designed using resistors and capacitors. Two LNA techniques, feedback amplifier and balanced amplifier, are simulated to find the best performance; the feedback amplifier provides a nominal noise figure of 1.02 dB and gain of 12 dB.
This document discusses different types of filters used to reduce noise in biomedical signals like EEG and ECG data. It describes low-pass filters which allow low frequencies to pass and block high frequencies, high-pass filters which do the opposite, and bandpass filters which combine a low-pass and high-pass filter to only allow a specific frequency range to pass. First order passive filters using a resistor and capacitor are demonstrated, as well as active filters using an op-amp. Digital filtering using LabVIEW is also introduced. Specific circuits are built and tested to filter simulated biomedical signals and analyze the filters' effects.
This document is a project report on developing a "Mobile Bug" circuit to detect unauthorized mobile phone usage. It includes sections on the concept and purpose of detecting mobile signals, a description of the circuit components and design, and diagrams of the circuit. The circuit uses a capacitor to capture RF signals from mobile phones, an op-amp chip to convert the signals to voltages, and a timer chip and transistor to trigger an LED and buzzer on detection. The report provides details on the components, including the op-amp and timer chips, and concludes with a list of components used in the circuit.
This project is a simple audio amplifier. It amplifies the audio signal to some extent. For amplifying purpose it used an IC and few more components. The heart of this amplifier is IC LM 386. The input to this circuit is given through the mobile phone or pc or any device which have 3.5mm connector.
1. Power dividers are microwave components that divide input power between output ports. Common types include T-junction, Wilkinson, and multi-section broadband dividers. T-junction dividers can be lossless or lossy. Wilkinson dividers provide isolation between output ports.
2. Directional couplers are 4-port networks that divide power between through and coupled ports. They use quarter-wave length lines and even-odd mode analysis. Voltage ratios define coupling factors. Multisection designs provide broadband operation.
3. Hybrids like the quadrature and ring hybrids are 90 or 180 degree hybrids based on symmetric/asymmetric port designs and even-odd mode analysis to provide specific scattering
Este documento describe diferentes medidas de dispersión como el rango, la desviación estándar y la varianza. Explica que estas medidas cuantifican cuán separados están los valores de una distribución de su media y cómo se dispersan a lo largo de la distribución. También introduce el coeficiente de variación como una medida de dispersión relativa que toma en cuenta la magnitud de los datos.
This document describes the design of a low noise amplifier (LNA) for wireless applications operating at 900 MHz. The LNA was implemented using a 0.13um RF CMOS technology and a cascode topology with inductive source degeneration. Simulation results showed the LNA has a gain of 26 dB, noise figure of 1.04 dB, input return loss of -14 dB, output return loss of -6.55 dB, reverse isolation of -39.76 dB, and power consumption of 115uW from a 2.5V supply. The LNA meets the requirements of low noise figure, high gain and low power consumption for a 900 MHz wireless application.
The Franklin oscillator circuit uses two FETs instead of vacuum tubes and provides a local oscillator signal of about 700mVpp for a balanced modulator generating single or double sideband amplitude modulated waves. It can be built in a screened box using common components like a ceramic coil former from an electric heater element, a double bearing tuning capacitor of 20pf, and a 5pf trimmer capacitor. With the addition of an LO amplifier and low pass filter, this Franklin oscillator design can generate a DSB/SSB signal for transmission on amateur radio bands like 80 meters.
IOSR journal of VLSI and Signal Processing (IOSRJVSP) is an open access journal that publishes articles which contribute new results in all areas of VLSI Design & Signal Processing. The goal of this journal is to bring together researchers and practitioners from academia and industry to focus on advanced VLSI Design & Signal Processing concepts and establishing new collaborations in these areas.
Equal Split Wilkinson Power Divider - Project PresentationBhanwar Singh Meena
This document discusses power dividers and describes the design of an equal-split Wilkinson power divider. It explains that a power divider splits an input power signal into two or more output signals of lower power. A Wilkinson power divider uses quarter wave transformers to split power in a 3dB ratio. The document then provides specifications for designing a Wilkinson power divider to operate at 2.4GHz using a substrate with permittivity of 3.38 and thickness of 1.524mm. It calculates the impedance values needed for the divider and uses a circuit design tool to calculate the microstrip line lengths and widths.
Directional couplers ppt for microwave engineeringDivya Shree
Directional couplers are passive microwave devices that divide power and distribute it through multiple ports. They have four ports: input, through, coupled, and isolated. Power entering the input port splits between the through and coupled ports, with some power coupled out through the coupled port. Directional couplers are characterized by their coupling factor, directivity, and isolation factor. They are used in applications such as power monitoring, signal sampling, and reflection coefficient measurements.
A low dropout (LDO) voltage regulator with high power supply rejection ratio (PSRR) and low
temperature coefficient (TC) is presented in this paper. Large 1μF off-chip load capacitor is used to
achieve the high PSRR. However, this decreases the gain and pushes the LDO’s output pole to lower
frequency causing the circuit to become unstable. The proposed LDO uses rail-to-rail folded cascode
amplifier to compensate the gain and stability problems. 2nd order curvature characteristic is used in
bandgap voltage reference circuit that is applied at the input of the amplifier to minimize the TC.
The characteristic is achieved by implementing MOSFET transistors operate in weak and strong
inversions. The LDO is designed using 0.18 μm CMOS technology and achieves a constant 1.8 V output
voltage for input voltages from 3.2 V to 5 V and load current up to a 128mA at temperature between -40 °C
to 125 °C. The proposed LDO is targeted for RF application which has stringent requirement on noise
rejection over a broad range of frequency.
A directional coupler is a passive device that couples part of the transmission power from one transmission line to another. It has four ports: input, transmitted, coupled, and isolated. Key parameters are coupling factor, loss, isolation, and directivity. Directional couplers are commonly used to monitor power and frequency without interrupting the main signal, for frequency and power measurements, and combining signals to a receiver when isolation is high.
A superheterodyne receiver, often shortened to superhet, is a type of radio receiver that uses frequency mixing to convert a received signal to a fixed intermediate frequency (IF) which can be more conveniently processed than the original carrier frequency. It was long believed to have been invented by US engineer Edwin Armstrong,
A high efficiency BPSK receiver for short range wireless networkTELKOMNIKA JOURNAL
1) The document describes a high efficiency BPSK receiver for short range wireless networks designed and simulated in 0.18 μm RFCMOS technology.
2) The receiver uses injection-locking techniques with a Colpitts oscillator to improve efficiency. It has a DC power of 0.474 mW and sensitivity of -60 dBm.
3) Simulation results show the receiver's oscillator has a phase noise of -160 dBc/Hz while consuming 0.377 mA from a 0.7 V power supply. The receiver can achieve a data rate of 5 Mbps with a figure of merit of 94 pJ/bit.
This document describes the design of a 16-channel audio mixer. It begins with an introduction to audio mixers and their uses. It then discusses the design methodology, considering factors like the number of input/output channels, power requirements, cost, and portability. The design is divided into several stages: a power stage using a step-down transformer and rectification circuit, a stereo stage for each channel with gain, bass, and treble controls, an auxiliary stage to boost the output signal, and a volume control stage to jointly control the levels. Block diagrams and circuit diagrams are provided to illustrate the design. In conclusion, the 16-channel audio mixer is tested by connecting it to an external amplifier and speakers.
This document describes the design of a lock-in amplifier micro-ohmmeter using Proteus VSM simulation software. It discusses the design in four stages: 1) the source stage containing an excitation oscillator, frequency divider and attenuator, 2) an instrumentation amplifier stage, 3) a filter stage, and 4) an output stage with a voltage controlled oscillator. Mathematical equations are provided for the components in each stage. The design of each stage is analyzed at the component level and verified through Proteus simulation. The simulation results matched the theoretical operation, confirming the successful design of the circuit using Proteus.
This document describes the design of an equal split Wilkinson power divider with the following specifications: frequency of 2.4 GHz, source and load impedances of 50 ohms, substrate permittivity of 3.38, substrate thickness of 1.524 mm, and conductor thickness of 0.15 mm. It provides background on Wilkinson power dividers, describes the calculation of microstrip line widths and lengths, shows the simulated circuit schematic and layout, and plots the resulting S-parameters which achieve the desired 3 dB power split with good port matching and isolation as expected.
Design of Ota-C Filter for Biomedical ApplicationsIOSR Journals
This document describes the design of an OTA-C filter for biomedical applications such as ECG signals. A fifth-order low pass Chebyshev filter with a cutoff frequency of 300Hz and power dissipation of 779nW was designed using a 0.18um CMOS process. Simulation results showed a gain of 22.5dB and CMRR of 93dB. The fully differential OTA-C filter provides higher common mode rejection and dynamic range compared to single-ended designs, while operating transistors in the sub-threshold region reduces power consumption. The proposed filter is suitable for low power portable biomedical applications.
Design of Low Noise Amplifier for Wimax ApplicationIOSR Journals
The document describes the design of a low noise amplifier (LNA) for WiMAX applications operating in the 3.3-3.8 GHz range. It discusses testing the transistor to check for stability and gain. Input and output matching is performed using stub matching networks to achieve low noise figure and high gain. A passive biasing circuit is designed using resistors and capacitors. Two LNA techniques, feedback amplifier and balanced amplifier, are simulated to find the best performance; the feedback amplifier provides a nominal noise figure of 1.02 dB and gain of 12 dB.
This document discusses different types of filters used to reduce noise in biomedical signals like EEG and ECG data. It describes low-pass filters which allow low frequencies to pass and block high frequencies, high-pass filters which do the opposite, and bandpass filters which combine a low-pass and high-pass filter to only allow a specific frequency range to pass. First order passive filters using a resistor and capacitor are demonstrated, as well as active filters using an op-amp. Digital filtering using LabVIEW is also introduced. Specific circuits are built and tested to filter simulated biomedical signals and analyze the filters' effects.
This document is a project report on developing a "Mobile Bug" circuit to detect unauthorized mobile phone usage. It includes sections on the concept and purpose of detecting mobile signals, a description of the circuit components and design, and diagrams of the circuit. The circuit uses a capacitor to capture RF signals from mobile phones, an op-amp chip to convert the signals to voltages, and a timer chip and transistor to trigger an LED and buzzer on detection. The report provides details on the components, including the op-amp and timer chips, and concludes with a list of components used in the circuit.
This project is a simple audio amplifier. It amplifies the audio signal to some extent. For amplifying purpose it used an IC and few more components. The heart of this amplifier is IC LM 386. The input to this circuit is given through the mobile phone or pc or any device which have 3.5mm connector.
1. Power dividers are microwave components that divide input power between output ports. Common types include T-junction, Wilkinson, and multi-section broadband dividers. T-junction dividers can be lossless or lossy. Wilkinson dividers provide isolation between output ports.
2. Directional couplers are 4-port networks that divide power between through and coupled ports. They use quarter-wave length lines and even-odd mode analysis. Voltage ratios define coupling factors. Multisection designs provide broadband operation.
3. Hybrids like the quadrature and ring hybrids are 90 or 180 degree hybrids based on symmetric/asymmetric port designs and even-odd mode analysis to provide specific scattering
Este documento describe diferentes medidas de dispersión como el rango, la desviación estándar y la varianza. Explica que estas medidas cuantifican cuán separados están los valores de una distribución de su media y cómo se dispersan a lo largo de la distribución. También introduce el coeficiente de variación como una medida de dispersión relativa que toma en cuenta la magnitud de los datos.
Randy Hoffman, Betty Chavis and Glen Hatton received the American Accounting Association's and Institute of Management Accounting's Jim Bulloch award in 2015 for their contribution to the education of managerial accounting.
Brent Lebow contributed to the game's prototyping by designing intricate logic puzzles and testing a physical prototype. He wrote the critical path for completing the game and worked with coders to implement puzzle choices. Brent also crafted the game's narrative by writing prompts, voice acting conversations, and color coding the narrative elements into the critical path and game world.
HPE's cloud strategy is focused on helping customers transform their infrastructure to a hybrid model. The strategy involves advising, migrating, and managing customers' workloads across private clouds, managed clouds, and public clouds. HPE aims to provide a unified experience for customers to deploy, manage and consume applications both on-premises and off-premises. The strategy also focuses on providing integrated services for billing, security, compliance and workload management across clouds.
This document presents the design of a high performance folded cascade OTA and sample and hold circuit. The OTA is designed to achieve 10-bit resolution while operating at a 28 MHz sampling frequency. Simulation results show the OTA achieves a high open loop gain of 72 dB and bandwidth of 112 MHz, with a phase margin of 73 degrees. A low resistance transmission gate switch is designed to reduce charge injection and clock feedthrough effects during sampling. The circuit is implemented in a 130 nm CMOS technology.
Automatic doorbell with object detectionAnurag Alaria
This document describes an automatic doorbell system that uses ultrasonic sensors to detect movement and ring a doorbell. It provides details on the components and circuit design of the transmitter and receiver modules that use ultrasonic waves to detect a person. The system is intended to automatically sense someone's presence and ring the doorbell, saving time and enhancing security compared to a traditional doorbell. The document includes circuit diagrams and descriptions of the main integrated circuits used, including the IC 555 timer and LM324 op-amp. It provides specifications and characteristics for the transistors and other components in the design.
This document describes a simple VHF receiver that can be built for around $20 using a superregenerative design. The receiver requires no special components or test equipment to construct. It uses a single JFET transistor as a superregenerative detector to provide high sensitivity of around 1 microvolt. The receiver can detect both AM and FM signals between 49-55 MHz with modifications allowing it to receive other VHF bands. With adjustments to the regeneration control and quench waveform control, the receiver can be tuned to receive narrowband FM transmissions with reasonable selectivity.
A simulator to reproduce fast rise-up noises which are generated when switching ON / OFF electric current on the inductive load.
It can be used for performance evaluation of electronic equipment upon reproduction of line noises which are intruded to the power supply lines or induced noises onto the telecommunication lines.
The document describes the Impulse Noise Simulator INS-S220. Key points:
- It can simulate high frequency noise such as that generated by switches or electric motors. This allows evaluation of electronic devices' noise resistance.
- The pulse width and repetition cycle can be adjusted, allowing tests with different pulse characteristics. Narrow pulses contain less energy but their fast transients still impact circuits.
- Using semiconductor relays instead of mercury improves pulse stability and allows more quantitative testing compared to older models.
- Settings are simplified through button operation rather than complex cable connections. This reduces setup time and errors.
- Various optional accessories allow different types of noise injection tests on electronic equipment under test.
This document describes the design and construction of a 2-meter or 4-element vertical dipole array antenna with gains of up to 9.7 dBi. The antenna consists of four or two vertical dipoles mounted on a fiberglass mast. Each dipole is made of 1/2 inch copper pipe and is fed individually to maintain 50 ohm impedances. A phasing harness built from 75 ohm coax is used to combine the signals in phase. Testing found communication ranges of up to 15 miles. The antenna breaks down into portable bags for transport and assembly takes under two hours with 2-3 people. The design provides an easy to build high gain antenna for repeater use.
A complete description of including circuit diagram, gain equation, features of Instrumentational amplifier , its working principle, applications, practical circuits, Proteus simulation and conclusion.
Uet, Peshawar Pakistan
Batch-06
A Review on Wide Bandwidth Low Noise Amplifier for Modern Wireless CommunicationIRJET Journal
This document reviews techniques for designing wide bandwidth low noise amplifiers for modern wireless communication. It discusses several techniques used in recent decades to improve the performance and linearity of low noise amplifiers, including wide range derivative superposition technique, direct-coupled amplifier topology, resistive shunt feedback topology, forward combining technique, and gate-inductive gain-peaking technique. The document also reviews the applications of low noise amplifiers in areas like low noise amplifier, distributed amplifier, broadband mixer, power amplifier and active balunes.
This document describes the design of a programmable gain linear pulse amplifier based on energy spectrum analysis. It uses a quasi-Gaussian CR-RC-CR shaping circuit structure with non-volatile digital potentiometers and precision operational amplifiers. This allows for multistage gain changes, low temperature drift, good pulse linearity, and stronger anti-jamming ability. The amplifier is used to amplify and filter nuclear detector output signals for analysis in multichannel spectrometers.
- Digital signal processing and its applications involve converting analog signals to digital signals using analog-to-digital conversion and processing digital signals using techniques like sampling.
- Sampling involves taking discrete measurements of a continuous signal at regular time intervals. The sampling rate must be at least twice the highest frequency of the original signal to avoid aliasing.
- Sample and hold circuits sample an analog input signal by connecting it to a capacitor, then hold the sampled value by disconnecting the capacitor, allowing time for analog-to-digital conversion without changes in the input affecting the held value.
Development of a receiver circuit for medium frequency shift keying signals.inventionjournals
Frequency shift keying (fsk) mode of digital signal information transfer switches between two predetermined frequencies of the carrier wave, either by modulating one sine wave oscillator or by switching between two oscillators.The need for a receiver to decode an fsk signal along the transmitting medium from a digital source code within about 5 kilometer radius for security monitoring of environment informed this work. The design of a receiver circuit at a frequency of 500 kHzfor an input frequency shift keying (fsk) signal from a transmitter is presented. The receiver is to receive an RF signal, amplify it, filter it to remove unwanted signals, and recover the desired base band information. It consists of an amplifier, tuned circuitsand mixers which filters the base-band information. A comparator circuit is incorporated, to detect the digital signal received. The output from the comparators is the digital equivalent of the coded signals sent by the transmitter circuit, and transferred to a microcontroller circuit, to act as a coded signal representing information from the transmitting end. The bode-plot response of the receiver to the incoming signals using a FET tuned circuit, shows that only frequencies above 470kHz, and below 495kHz are allowed to pass through the network with a resonant frequency of 483.553 kHz and a gain of 27.734dB, while others are totally attenuated. The reliability of the designed receiver circuit was evaluated for a 1 year continuous operating period and was found to be 74.7%.Area of application of this work include electronic policing of a defined environment with good success
• Designed a Wilkinson Combiner at 30 GHz using microstrip transmission line and then at 60 GHz using coplanar waveguide.
• Simulated the Layout of the testbench using the EM Simulator at RF.
A 10 d bm 25 dbm, 0.363 mm2 two stage 130 nm rf cmos power amplifierVLSICS Design
This document summarizes the results of simulating a two-stage 130nm RF CMOS power amplifier designed for 2.4GHz applications. The power amplifier was simulated with variations in supply voltage from 1V to 5V and size of the second stage transistor from 150um to 500um. Supply voltage significantly impacted output power, ranging from 10.684dBm to 25.08dBm at 1dB compression point. Transistor size also impacted output power but to a lesser degree, from 15.47dBm to 20.338dBm. Power added efficiency was maximized at intermediate supply voltages and transistor sizes, from 16.65% to 48.46% and 29.085% to 45.439% respectively
1) The document describes the design and simulation of a linear amplifier that operates in the C band frequency range of 5-6 GHz.
2) A Class A amplifier design approach was used to ensure linearity at higher frequencies. A GaAs FET transistor was selected and biased in its linear region.
3) Input and output matching networks were designed using S-parameter simulations. Multiple transistor stages were cascaded to increase the gain to 30 dB.
4) Simulation results showed a gain of 19.241 dB, S-parameters, stability above 1, and a noise figure of around 3 dB as expected for a low noise pre-amplifier.
This document provides details on the design and specifications of the Q-Watt audio power amplifier developed by Elektor Labs. The amplifier uses a single pair of complementary output transistors and the LME49811 audio power amplifier IC to deliver over 200 watts of power into 4 ohms with low distortion. Key features include an input sensitivity of 0.88V, a frequency response of 2.1Hz to 125kHz at 50W/8ohms, total harmonic distortion below 0.1% at 1kHz and 50W/8ohms, and an efficiency of over 70%. The circuit and performance measurements are described in detail.
An operational amplifier with recycling folded cascode topology and adaptive ...VLSICS Design
This paper presents a highly adaptive operational amplifier with high gain, high bandwidth, high speed
and low power consumption. By adopting the recycling folded cascode topology along with an adaptivebiasing
circuit, this design achieves high performance in terms of gain-bandwidth product (GBW) and slew
rate (SR). This single stage op-amp has been designed in 0.18μm technology with a power supply of 1.8V
and a 5pF load. The simulation results show that the amplifier achieved a GBW of 335.5MHz, Unity Gain
Bandwidth of 247.1MHz and a slew rate of 92.8V/μs.
Two-section branch-line hybrid couplers based broadband transmit/receive switchIJECEIAES
This article introduces a broadband microstripline-based transmit/receive switch for 7-Tesla magnetic resonance imaging. The designed switch aims to handle a signal of multiple frequencies to/from a multi-tuned radio-frequency coil that resonates at frequencies corresponding to the speed of precession of a wide range of atomic X-nuclei, at the same time and without tuning. These include 1H, 23Na, 13C, 31P, 19F, and 7Li used in magnetic resonance spectroscopy as a measure to the existence of many diseases. The fundamental and third harmonic center frequencies of the switch are adjusted to resonate at two broadbands covering a wide range of atomic X-nuclei. Two section branch-line hybrid couplers with phase inverters are designed to build the broadband switch. The designed switch used the minimum trace widths of transmission lines that reveal a compact size without increasing the heat and then the loss beyond specific values. The couplers and the switch S-parameters exhibited good return loss (<-10 dB), high isolation (<-40 dB), less insertion loss (<1 dB) and two clear wide bands covering many atomic X-nuclei used in diagnosis, at the same time and without the need for any tuning circuit during operation.
This document describes the design and construction of an active antenna called the AA-7 that can amplify radio signals from 3 to 3000 MHz. It contains two independent preamplifiers that can be selected using a switch. One preamplifier is optimized for HF signals using a MOSFET and the other is for VHF/UHF using an NPN transistor. The circuit board layout and assembly instructions are provided to allow homemade construction. The active antenna requires minimal external components and can be built on a small printed circuit board, making it compact and portable. It is powered by a single 9V battery and does not require an enclosure, though one can be added.
The document discusses different types of impedance matching networks and filters used in radio circuits. It provides details on L-networks, Pi-networks, low-pass filters, high-pass filters, band-pass filters, band-stop filters, crystal ladder filters, and their use in receiver input circuits. Design procedures and equations for calculating component values for low-pass and band-pass filters are also summarized.
Sinewave Generation 1. Problem Statement The goal of t.docxjennifer822
Sinewave Generation
1. Problem Statement
The goal of this project is to generate a sinusoidal waveform with the Arduino. Software is
provided that outputs a binary sinewave signal on pins D8-D11 which is converted to an
analogue voltage using a special type of digital to analogue converter (DAC), called an R-2R
ladder. The sinewave's frequency is roughly 200 Hz. Your task is to design and construct
both the R-2R ladder and a reconstruction filter which converts the “staircase” output of the
R-2R DAC into a “smooth” sinusoidal signal of amplitude 3 Vpk-pk and mean value zero.
2. Background
Many modern devices utilise digital circuits for analysing and processing data but still require
an interface to the analogue world, for example, to drive a speaker or control a motor's speed.
The conversion of digital data to analogue voltages is performed with a circuit known as a
digital to analogue converter, or DAC. In this project you will be implementing a simple
DAC circuit built solely of resistors, called the R-2R ladder.
To generate an analogue signal DACs will update their output at a specified frequency known
as the sample rate. The DAC's output voltage will only change value once per sample,
resulting in a “staircase” looking waveform. In order to produce a smooth waveform a circuit
known as a reconstruction filter is used. There are many different ways of implementing this
filter but in this project you will use a combination of active (op-amp based) low-pass and
high-pass filters.
2.1. R-2R ladder
The R-2R ladder DAC uses a network of resistors to convert a binary number to an analogue
voltage. The digital number is given from the Arduino by the digital output pins. In fact
these pins act as a controlled voltage source. If a bit in the 4-bit binary represented number is
1, the corresponding output pin is set HIGH and acts as a voltage source. If the bit is 0 on the
other hand, the corresponding output pin is set LOW and acts as a ground connection.
Although simple this circuit has several limitations. Specifically, it has a high output
impedance (ie: the Thevenin equivalent resistance is high) and the precision of the output
voltage is limited by the low number of bits and the precision of the resistors chosen. The
1% tolerance resistors available in the lab become the limiting factor beyond 6 bits so this
DAC architecture is rarely used for high precision DACs (10+ bits).
In this project you can use op-amp circuits to act as buffers to compensate for the high output
impedance of the R-2R ladder. The precision of the output will be limited by the chosen 4-bit
bit depth and will result in “noise” on the output (ie: random voltage amplitude errors) which
are impractical to remove. Nonetheless a smooth-looking waveform should still be possible
to generate.
The basic circuit is shown in Figure 1.
Exercise 1. Find expressions for the output (Vout) in terms o.
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
Understanding Inductive Bias in Machine LearningSUTEJAS
This presentation explores the concept of inductive bias in machine learning. It explains how algorithms come with built-in assumptions and preferences that guide the learning process. You'll learn about the different types of inductive bias and how they can impact the performance and generalizability of machine learning models.
The presentation also covers the positive and negative aspects of inductive bias, along with strategies for mitigating potential drawbacks. We'll explore examples of how bias manifests in algorithms like neural networks and decision trees.
By understanding inductive bias, you can gain valuable insights into how machine learning models work and make informed decisions when building and deploying them.
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
objectivity. This study analyze primary and secondary research documents critically to elaborate role of
china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
China is seeing significant success in commerce, pipeline politics, and gaining influence on other
governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
Comparative analysis between traditional aquaponics and reconstructed aquapon...bijceesjournal
The aquaponic system of planting is a method that does not require soil usage. It is a method that only needs water, fish, lava rocks (a substitute for soil), and plants. Aquaponic systems are sustainable and environmentally friendly. Its use not only helps to plant in small spaces but also helps reduce artificial chemical use and minimizes excess water use, as aquaponics consumes 90% less water than soil-based gardening. The study applied a descriptive and experimental design to assess and compare conventional and reconstructed aquaponic methods for reproducing tomatoes. The researchers created an observation checklist to determine the significant factors of the study. The study aims to determine the significant difference between traditional aquaponics and reconstructed aquaponics systems propagating tomatoes in terms of height, weight, girth, and number of fruits. The reconstructed aquaponics system’s higher growth yield results in a much more nourished crop than the traditional aquaponics system. It is superior in its number of fruits, height, weight, and girth measurement. Moreover, the reconstructed aquaponics system is proven to eliminate all the hindrances present in the traditional aquaponics system, which are overcrowding of fish, algae growth, pest problems, contaminated water, and dead fish.
International Conference on NLP, Artificial Intelligence, Machine Learning an...gerogepatton
International Conference on NLP, Artificial Intelligence, Machine Learning and Applications (NLAIM 2024) offers a premier global platform for exchanging insights and findings in the theory, methodology, and applications of NLP, Artificial Intelligence, Machine Learning, and their applications. The conference seeks substantial contributions across all key domains of NLP, Artificial Intelligence, Machine Learning, and their practical applications, aiming to foster both theoretical advancements and real-world implementations. With a focus on facilitating collaboration between researchers and practitioners from academia and industry, the conference serves as a nexus for sharing the latest developments in the field.
The Python for beginners. This is an advance computer language.
July 24, 2003
1. www.edn.com July 24, 2003 | edn 81
ideas
design
Edited by Bill Travis
U
sing a capacitive-cou-
pled clip, you can pick
up the signal from a
twisted-pair or -wire tele-
phone line or from other un-
shielded analog lines with-
out piercing the insulation.
No line test can detect the
clip’s presence, and it leaves
no evidence of hav-
ing been attached. It
needs no ground return.You
can fasten the small, insulat-
ed pickup plates to the op-
posing jaws of an alligator clip for quick
and easy attachment.Balanced lines from
the plates connect to the inputs of a high-
impedance differential amplifier (Figure
1). For this scheme to have satisfactory
signal-to-noise and frequency-response
parameters, the clip, connecting cable,
and amplifier must m be attached paral-
lel to the signal wire and must be as long
as is conveniently possible—an inch or
more—and preferably slightly curved to
maximize the coupling capacitance. (For
a twisted-conductor line, the plates
should not be longer than the twist
“wavelength” to avoid signal cancella-
tion.) You should orient the clip for the
cleanest signal output.
The clip, its connecting cable, and the
amplifier must be shielded to minimize
interference, typically comprising 60-Hz
signals and their harmonics from power-
line fields. The cable should have good
electrical symmetry and low total capac-
itance between conductors and to the
shield. Thus, the amplifier must be near
the clip. The amplifier should have high
input resistance, low current noise, and
adequate common-mode rejection.
The clip’s coupling capacitance and
stray capacitance and the amplifier’s in-
put resistance determine the low-fre-
quency cutoff of the detected signal.Stray
capacitances in the clip and in its con-
necting cable to the shield are generally
much larger than the coupling capaci-
tance. Thus, voltage-divider action re-
duces the signal,but the stray component
adds to the capacitance the amplifier’s in-
put sees and reduces the cir-
cuit’s noise by the square root
of the signal attenuation. The
noise reduction accrues from
reducing the needed input re-
sistance. Therefore, you gen-
erally don’t need the compli-
cation of an insulated “boot-
strapped” shield. You can fol-
low the amplifier with a near-
by or remotely located post-
amplifier for more gain and
bandpass filtering to opti-
mize the signal-to-noise per-
formance.A telephone signal has a band-
width of approximately 300 Hz to 3 or 4
kHz. A sharp highpass cutoff at 300 Hz
effectively rejects power-line noise pick-
up. A simple, two-pole, Sallen-Key But-
terworth filter works well.You can trim it
to provide some high-frequency peaking
to obtain the most intelligible signal.
A multiple-pad pickup scheme im-
proves noise rejection (Figure2).The cir-
cuit’s arrangement is such that even-
numbered pads on one side and
odd-numbered pads on the other side
pick up equal noise that produces oppo-
site-phase outputs from op amps A and
B. Op amp C then sums the signals and
rejects the noise. The desired difference
signal, however, appears in-phase at the
outputs of A and B,so both op amps con-
+
–
TO POSTAMPLIFIER
OP
AMP
R
RVS
(CABLE
SIGNAL)
VCM
60 Hz+HARMONICS
C1
CCOUPLING CSTRAY
TOTAL
AMPLIFIER RIN
C2
C3
C4
C5
Figure 1
Clip extracts signal from phone line
Maxwell Strange, Fulton, MD
In this equivalent circuit, you should maximize the coupling capacitances, C1
and C2
, and minimize the stray capacitances, C3
, C4
, and C5
.
+
–
C
+
–
B
+
–
A
RGAIN
OUTPUT
R
R
A
D
B
C
PHONE LINE
CLIP
PADS
Figure 2
A multiple-pad approach produces cancellation of equal noise that the opposed pad pairs pick up. Clip extracts signal from phone line..........81
Circuit produces variable frequency,
duty cycle ........................................................82
Active-feedback IC serves as current-
sensing instrumentation amplifier ............86
Create secondary colors
from multicolored LEDs................................88
Publish your Design Idea in EDN. See the
What’s Up section at www.edn.com.
2. 82 edn | July 24, 2003 www.edn.com
ideas
design
tribute equally to the output. You can
make a segmented pickup from pieces of
two-sided pc board with the solid-copper
side serving as a shield.You can solder the
shield side of the pieces to a suitable alli-
gator clip. Alternatively, for longer term
use, you can simply tape them onto the
cable. You can use any even number of
pads. the more you use, the better, but
eight on each side are sufficient.
The amplifier of Figure 3 uses two
quad J-FET or BiFET op amps.Thanks to
stray capacitance on the input lines of the
test model, a relatively low input resist-
ance of 3.3 M⍀ is sufficient. Input noise
is mostly the Johnson noise of the 10-M⍀
feedback resistors.Power-line noise pick-
up is usually the bigger problem. The
output stages incorporate some highpass
filtering to reject noise below 300 Hz.The
output level depends on many factors but
is approximately 50 mV. A postamplifier
(not shown) can provide more equaliza-
tion, filtering, and gain if necessary, as
well as manual or automatic level control.
Tests of models of both design ap-
proaches use readily available compo-
nents and show perfectly clear telephone
speech through a small speaker in the
postamplifier box. The multiple-pad
pickup system produces noticeably low-
er noise, and clip orientation is less crit-
ical.˿
_
+
IC1B
_
+
IC1A _
+
IC2A
_
+
IC2C
NOTES:
IC1 AND IC2 ARE QUAD JFET OP AMPS.
CAPACITORS ARE Ϯ20% CERAMIC._
+
IC1D
_
+
IC1C
_
+
IC2B
3.3M
D
C
B
A
3.3M
10M
10M
10M
10MINPUT FROM
MULTISEGMENT
PICKUP
3.3M
X
X
9V
SHIELD AND
POWER GROUND
SHIELD
3.3M
3.3M
3.3M
R
150k
R
R
150k
0.0015 µF
0.01
µF
0.01
µF
1 µF
1 µF
1 µF
150k
10k
OP-AMP
+POWER
OP-AMP
מPOWER
220k
R
R
R
150k
OUTPUT
3.3k
150 pF
_
+
IC2D
R
Figure 3
This amplifier, using the multiple-pad approach effectively reduces power-line-related noise pickup.
T
his Design Idea shows a simple,
low-cost circuit that produces a high-
ly accurate variable-frequency and
variable-duty-cycle output (Figure 1).
Further, the duty cycle and frequency are
independent of each other (excluding 0
and 100% duty cycle). The method de-
rives its accuracy and stability from the
fact that the output is based on a crystal
oscillator and divisions of the oscillator’s
frequency. The design uses only six de-
vices. IC1
, a 74HC393 binary ripple
counter, has as its input is the oscillator’s
output frequency.The outputs are the os-
cillator frequency divided by two, four,
eight, 16, 32, 64, 128, and 256. IC5B
is cas-
caded with IC1
to divide the oscillator fre-
quency further by 512, 1024, 2048, and
4096. In this circuit, the divide-by-128 is
the largest division it uses. You could,
with a simple wiring change, substitute
an unused divider to obtain a different
output-frequency range.The eight inputs
of IC2
,a 74HC151 eight-line-to-one-line
multiplexer, connect to the oscillator’s
frequency divided by one, two, four,
eight, 16, 32, 64, and 128. Note that the
oscillator’s output connects directly to an
input of IC2
. This connection allows se-
lecting the oscillator’s frequency divided
by one. IC2
connects one of the eight fre-
quencies to the input of IC3
.
IC3
, a 74HC4017 decade counter, di-
Circuit produces variable frequency, duty cycle
Mark Reed, Texas Instruments, Dallas, TX
3. 84 edn | July 24, 2003 www.edn.com
ideas
design
vides the frequency from IC2
’s output by
10. Therefore, the maximum output fre-
quency for this design is the oscillator fre-
quency divided by 10. Each of the decod-
ed decade counter’s 10 outputs goes high
for one clock cycle only (Figure
2). Using the 10 outputs, a fre-
quency’s period divides
into 10 equal intervals.You
can use these 10 equal intervals
to generate duty cycles of 10, 20,
30, 40, 50, 60, 70, 80, and 90%.
For this circuit, the outputs of
IC3
, Q1 through Q8, yield the
end-of-pulse signals for duty cy-
cles of 10 through 80%, respec-
tively.The start-of-pulse signal is
Q9’s negative edge,which occurs
at the same time as Q0’s positive
edge. Therefore, you can use Q9
as start-of-pulse low true, and
the end-of-pulse signals are high
true. The eight inputs of IC4
, an
eight-line-to-one-line multi-
plexer, connect to eight of the
nine end-of-pulse outputs from
IC3
. This circuit omits the 90%
duty cycle. You can include the
90% duty cycle with a simple
wiring change. If you want to select 0%
duty cycle,connect an input to IC4
.If you
select 0% duty cycle, the generator’s out-
put is low. IC4
connects one of eight end-
of-pulse signals to IC5
.
IC5A
is a binary ripple counter that
serves as a set-reset latch. The start-of-
pulse signal sets the latch. The end-of-
pulse signal resets the latch. The output
of IC5
is the variable-frequency and vari-
able-duty-cycle output of the
signal generator. For example,
if the oscillator’s frequency is 4
MHz and IC2
’s C B A inputs
are 0 1 0, then the generator
delivers 100 kHz.If IC4
’s C BA
inputs are 0 0 1, then the gen-
erator’s output exhibits 20%
duty cycle.If you need to select
from more than eight fre-
quencies, use a larger multi-
plexer than IC2
. Cascade more
or different types of dividers to
achieve your frequency needs.
You can use a 74HC390 to ob-
tain division by five, 10, 50,
100, and so on. If you need
other duty cycles, cascade
74HC4017s to divide the pe-
riod by the desired number of
intervals. Finally, if you need
to select from more than eight
duty cycles, use a larger mul-
tiplexer than IC4
.˿
CLK
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Q8
Q9
START-OF-PULSE
END-OF-PULSE
10% DUTY CYCLE
END-OF-PULSE
20% DUTY CYCLE
END-OF-PULSE
30% DUTY CYCLE
END-OF-PULSE
40% DUTY CYCLE
END-OF-PULSE
50% DUTY CYCLE
END-OF-PULSE
60% DUTY CYCLE
END-OF-PULSE
70% DUTY CYCLE
END-OF-PULSE
80% DUTY CYCLE
END-OF-PULSE
90% DUTY CYCLE
IC3
Figure 2
The end-of-pulse signals from IC4
determine the duty cycle of the
output waveform.
QA
QB
QC
QDCLR
11
/512
/1024
/2048
/4096
10
9
812
13
IC5A
QA
QB
QC
QDCLR
11
10
9
812
DGND
7
DGND
DGND
13
IC1B
QA
5V
Y1
QB
QC
QDCLR
Q0
Q1
Q2
Q3
Q4
Q5
Q6
Q7
Q8
Q9
CO
CLK
3
4
5
62
DGNDDGND
GND OUT
EN
1
1
4
5
8
CLK
CLK
IC1AVCC
IC3
12
13
14
15 6
5 14
13
15
1
2
3
SET
FREQUENCY
4
9
10
11
/128
/256
/64
/32
/16
/8
/4
/2
/1
CI
CLK
RST
7
DGND
C B A
OSCILLATOR
FREQUENCY
DIVIDE BY
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
10
20
40
80
160
320
640
1280
DGND
A
B
C
D0
D1
D2
D3
D4
D5
D6
D7
IC4 IC5B
12
13
14
15 6
5
1
2
START OF
PULSE
END OF
PULSE
1
2
3
SET
DUTY CYCLE
4
9
10
11
80%
70%
60%
50%
40%
30%
20%
10%
W
Y
12
3
11
9
6
5
1
10
7
4
2
QA
QB
QC
QD
3
1
GENERATOR
OUTPUT
4
5
6
C B A DUTY CYCLE (%)
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
0
1
0
1
0
1
0
1
10
20
30
40
50
60
70
80
74HC393N
74HC393N
74HC393N
G
A
B
C
D0
D1
D2
D3
D4
D5
D6
D7
IC2
W
Y
74HC151N
74HC151N 74HC393N
74HC4017N
SET_FREQ_C
SET_FREQ_B
SET_FREQ_A
SET_DUTY_C
SET_DUTY_B
SET_DUTY_A
CLR
CLK
G
Figure 1
This circuit produces waveforms of variable frequency and duty cycle. Further, the frequency and duty cycle are independent of each other.
4. 86 edn | July 24, 2003 www.edn.com
ideas
design
H
igh-speed current
sensing presents a de-
signer with some sig-
nificant challenges. Most
techniques for sensing cur-
rent involve measuring the
differential voltage the cur-
rent produces as it flows
through a sense element,
such as a resistor or a
Hall-effect device. The
differential voltage across
the sense element is gener-
ally small and is often riding
on a common-mode voltage
that is considerably larger
than the differential voltage
itself. Accurate amplifica-
tion of the differential voltage requires a
differential amplifier with high input im-
pedance, high CMR (common-mode re-
jection); wide input-common-mode
voltage range; and high, well-defined
gain.Traditional instrumentation ampli-
fiers have these features and often serve
for low-frequency current sensing, but
they perform poorly at high speeds.
High-speed current sensing requires the
kind of performance that instrumenta-
tion amps provide, but their abilities
must extend to high fre-
quencies. Figure 1 shows
how high-speed active
feedback amplifiers, such
as the AD8129 and AD-
8130 differential receivers,
are ideal for these high-
speed instrumentation-
amp applications. The
AD8129 requires a mini-
mum closed-loop voltage
gain of 10 for stability,
whereas the AD8130 is
unity-gain-stable.
Active-feedback ampli-
fier operation differs
from that of traditional
op amps; it provides a
beneficial separation between the sig-
nal input and the feedback network.
Figure 1 shows a high-level block dia-
gram of an active-feedback amplifier in
a typical closed-loop configuration.
High-speed current sensing uses a re-
sistor as the sense element. The input
stages are high-impedance, high-CMR,
wideband, high-gain transconductance
amplifiers with closely matched trans-
conductance parameters. The output
currents of the transconductance am-
plifiers undergo summing, and the
voltage at the summing node is
buffered to provide a low-impedance
output. Applying negative feedback
around amplifier B drives VOUT
to a lev-
el that forces the input voltage of am-
plifier B to equal the negative value of
the input voltage at amplifier A, be-
cause the current from amplifier A
equals the negative value of the current
from amplifier B, and the gm values are
closely matched. From the foregoing
discussion, you can express the closed-
loop voltage gain for the ideal case as:
VOUT
/VIN
ϭ1ϩRF
/RG
ϵAV
.
Measurement sensitivity in volts per
ampisexpressedas:VOUT
/ISENSE
ϭAV
RSENSE
.
Minimizing the values of RF
and RG
also
minimizes resistor and output-voltage
noise arising from input-referred current
+
+
–
–
+
–
gm
A
+
–
gm
B
ISENSE RSENSE
RF
RG
IOUT
VOUT
VSENSE
ϫ1
AD8129/30
Figure 1
Active-feedback IC serves as
current-sensing instrumentation amplifier
Jonathan Pearson, Analog Devices, Wilmington, MA
An active-feedback amplifier is ideal for current-sensing applications.
+
–
gm
+
–50
ϫ1
AD8129
1
33 pF 33 pF50
NETWORK-ANALYZER Rx
NETWORK-ANALYZER Tx
150 nH
100-MHz, THREE-POLE BUTTERWORTH
LOWPASS FILTER
50
50
15.8
301
gm
Figure 2
This test circuit produces flat frequency response to 10 MHz.
5. 88 edn | July 24, 2003 www.edn.com
ideas
design
noise. Because of the small sense resist-
ance and high measurement frequencies,
you must minimize parasitic effects in the
input circuitry to avoid measurement er-
rors. Parasitic trace inductance in series
with the sense element is of particular
concern,because it causes the impedance
across the amplifier’s input to increase
with increasing frequency, producing a
spurious increase in output voltage at
high frequencies. Figure 2 illustrates a
test circuit with RSENSE
ϭ1⍀ and AV
ϭ20,
which equates to a measurement sensi-
tivity of 20V/A. The three-pole lowpass
filter produces a defined bandwidth and
attenuates spurious responses at the am-
plifier’s output arising from input signals
at frequencies outside the desired meas-
urement bandwidth.The test circuit’s fre-
quency response in Figure 3 shows that
the expected differential-to-single-ended
gain of 20/101, or Ϫ14 dB, is flat to
approximately 10 MHz and is down
by 3 dB at 62 MHz. Figure 3 demon-
strates the effectiveness of the high CMR
of active-feedback amplifiers. The com-
mon-mode signal at the amplifier’s input
is approximately 50 times greater than
the differential signal across the sense re-
sistor.˿
Figure 3
The test circuit in Figure 2 exhibits accurate
differential gain in the presence of large com-
mon-mode signals.
I
t is well-known that simultaneous-
ly mixing two primary-color light
sources,such as red and green,creates
a secondary color, such as yellow. This
mixing process commonly occurs in tri-
color LEDs. One disadvantage of this
method of generating a yellow color is
that the LED must use twice the cur-
rent because both the red and the
green LEDs must be on. In battery-pow-
ered circuits,the LED indicator’s operat-
ing current may be a significant fraction
of the supply current, so using the same
current to generate both primary and
secondary colors is advantageous. The
operating-current savings may be signif-
icant in telecom-line-card applications
involving thousands of line cards or
large-panel RGB LED displays. This De-
sign Idea proposes a sequencing method
to generate balanced secondary colors
from bicolor,tricolor,and RGB LEDs,us-
ing only one LED’s operating cur-
rent.Advantages include lower pow-
er dissipation and more uniform in-
tensities between primary and secondary
colors.Using the sequencing method also
allows a bicolor LED to now produce
three colors and keep a simpler pc-board
layout using two rather than three pins.
In addition, you can also produce white
light with RGB LEDs using the sequenc-
ing method.
The method uses the property of im-
ages to persist in the human eye for sev-
eral tens of milliseconds. If different pri-
mary colors flash sequentially and quick-
ly enough from one point, humans see
them as overlapping in time, and the
brain interprets them to appear as sec-
ondary colors or even white, depending
on the color components. Experimenta-
tion with two or three primary-color
LEDs shows that the flash sequence must
complete within approximately 25 msec
or less to produce a solid secondary col-
or or white light. In testing for an upper
limit, you can use flash rates to 1 MHz to
produce this effect without degrading
secondary colors. Thus, you can use any
convenient clock source higher than 40
Hz to create secondary colors. Note that
R1 R4
VCC
R2
A
B
RC
GC
CA
LED 1
BILEDCA
R5
VCC
R7
A
C
RC
BC
R6
B
GC CA
LED 4
TRILEDCA
VCC
A
B
RC R3
B
A RC GC
GC
CA
LED 2
BILEDCA
LED 3
BILED
NOTES:
CA=COMMON ANODE.
CC=COMMON CATHODE.
Figure 1
Create secondary colors from multicolored LEDs
Claude Haridge, Stittsville, ON, Canada
All these LED configurations can produce secondary colors, either by current control or
duty-cycle control.
LEDs OFF RED LED ON GREEN LED ON YELLOW
f>40 Hz
5V
0V
5V
0V
A
B
5V
0V
5V
0V
A
B
tGREEN tRED
t<25 mSEC
Figure 2
The waveforms at the top generate yellow
from green and red; the same result ensues
from duty-cycle control (bottom right).
6. 90 edn | July 24, 2003 www.edn.com
ideas
design
the primary-color LEDs must be physi-
cally close together, such as on a semi-
conductor chip, for the eye to properly
mix the light. Diffused lenses also allow
a wider viewing angle. These combina-
tions are commercially avail-
able as bicolor, tricolor, and
RGB LEDs.
Figure 1 shows the various
LED-circuit configurations,
and Figure 2 shows the timing
to generate all three colors
from bicolor and tricolor
LEDs, although using only one
LED’s operating current. Note
that the driver for the bicolor
LED must be able to sink and source cur-
rent.You may have to provide color bal-
ance between the primary-color LEDs to
ensure that the secondary colors appear
properly. The LEDs have different effi-
ciencies and intensities as the human eye
sees them, and these parameters need
correcting. For tricolor LEDs in a com-
mon-anode or -cathode configuration
and 50% duty cycle, the correction is
easy to effect by adjusting the current-
limiting resistors. Alternatively, you can
use one current-limiting resistor and
then vary the duty cycle to provide the
necessary color balance.For two-leaded,
bicolor LEDs, it is easier to adjust the
duty cycle to produce the correct sec-
ondary color than to use additional cir-
cuitry. The waveforms at the bottom of
Figure 2 illustrate duty-cycle control to
achieve secondary-color balance for
both bicolor and tricolor LEDs.
Using a sequenced bicolor LED to
generate three colors has packaging ad-
vantages, particularly when you verti-
cally stack several LEDs. Previously,
stacked, tricolor LEDs need-
ed to use a through-hole as-
sembly, because the middle
lead would be inaccessible if
the devices were surface-
mounted. Because the bi-
color LED has only two
pins, you can vertically stack
several of them and bend
out the leads for surface
mounting. The generation
of secondary colors can also extend to
RGB LEDs (Table 1). You can achieve
color balancing by adjusting the cur-
rent-limiting resistors or the duty cycle.
You can program three pins from a mi-
crocontroller’s port to sequence through
the various primary-color combina-
tions.˿
TABLE 1—SECONDARY COLORS FROM RGB LEDs
Red Green Blue Emitted color Notes
0 0 0 None
1 0 0 Red
0 1 0 Green
0 0 1 Blue
1 1 0 Yellow Red/green sequenced
0 1 1 Cyan Green/blue sequenced
1 0 1 Magenta Blue/red sequenced
1 1 1 White Red/green/blue sequenced