The document discusses interleaved analog-to-digital converters (ADCs). It begins by explaining that interleaving multiple ADCs allows for an effective sample rate that is a multiple of the individual ADCs' rates. This provides benefits like increased bandwidth. The document then discusses the basics of how interleaving works using clock phase relationships. It explains that while interleaving provides advantages, there are also challenges in the form of mismatches between the ADCs that can cause spurs in the output spectrum. Specifically, it outlines offset, gain, timing, and bandwidth mismatches. The document concludes by stating that knowing about and addressing these mismatches enables the effective use of interleaved ADCs to meet demanding application requirements.
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Optimum FIR Filtersfor Digital Pulse Compression of Biphase Barker Codes with...IJERA Editor
In Wireless signals and Radar signals where power, real estate, speed and low cost are tight constraints and
Doppler tolerance is not a major concern biphase codes are popular and FIR filter is used for digital pulse
compression (DPC) implementation to achieve required range resolution. Disadvantage of low peak to sidelobe
ratio (PSR) of biphase codes can be overcome by linear programming for either single stage mismatched filter
or two stage approach i.e. matched filter followed by sidelobe suppression filter (SSF) filter. Linear
programming (LP) calls for longer filter lengths to obtain desirable PSR. Longer the filter length greater will be
the number of multipliers, hence more will be the requirement of logic resources used in the FPGAs and many
time becomes design challenge for system on chip (SoC) requirement.
This requirement of multipliers can be brought down by clustering the tap weights of the filter by kmeans
clustering algorithm at the cost of few dB deterioration in PSR. The cluster centroid as tap weight reduces logic
used in FPGA for FIR filters to a great extent by reducing number of weight multipliers. Since kmeans
clustering is an iterativealgorithm, centroid for weights cluster is different in different iterations and causes
different clusters. This causes difference in clustering of weights and sometimes even it may happen that lesser
number of multiplier and lesser length of filter provide better PSR.
In this paper few sample optimum biphase codes have been provided in tabular form with their optimum
sidelobe supression filter (SSF) with optimum lengths and minimum multipliers to achieve low sidelobe level of
-35 dBto -40 dB and have been compared against PSR achieved without clustering.Clustering is used in FIR
filter for pulse compression and its effect is seen on peak to sidelobe ratio. This is being a genericmethod for
FIR filters to reduce number of multipliers can be extended to other similar applications.
PERFORMANCE EVALUATION OF ADAPTIVE ARRAY ANTENNAS IN COGNITIVE RELAY NETWORKcsijjournal
Adaptive Array Antennas (AAAs) are expected to play a key role in meeting the demands of the wireless communication systems of the future. AAAs in cognitive relay network is proposed to reduce the symbol error rate and improve the system performance. Many algorithms such as wiener solution and least mean square (LMS) will be explained to show how AAAs in cognitive relay network achieves this object. AAAs at different locations will be investigated under AWGN and Rayleigh fading channel. Moreover, enhancement the system performance by showing the effect of increasing the number of AAAs element at the relay node, increasing the source gain and decreasing the relay gain. In addition, increasing the rate adaptation and number of iterations in LMS algorithm has significant improvement in the system.
IOSR Journal of Electronics and Communication Engineering(IOSR-JECE) is an open access international journal that provides rapid publication (within a month) of articles in all areas of electronics and communication engineering and its applications. The journal welcomes publications of high quality papers on theoretical developments and practical applications in electronics and communication engineering. Original research papers, state-of-the-art reviews, and high quality technical notes are invited for publications.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology
Optimum FIR Filtersfor Digital Pulse Compression of Biphase Barker Codes with...IJERA Editor
In Wireless signals and Radar signals where power, real estate, speed and low cost are tight constraints and
Doppler tolerance is not a major concern biphase codes are popular and FIR filter is used for digital pulse
compression (DPC) implementation to achieve required range resolution. Disadvantage of low peak to sidelobe
ratio (PSR) of biphase codes can be overcome by linear programming for either single stage mismatched filter
or two stage approach i.e. matched filter followed by sidelobe suppression filter (SSF) filter. Linear
programming (LP) calls for longer filter lengths to obtain desirable PSR. Longer the filter length greater will be
the number of multipliers, hence more will be the requirement of logic resources used in the FPGAs and many
time becomes design challenge for system on chip (SoC) requirement.
This requirement of multipliers can be brought down by clustering the tap weights of the filter by kmeans
clustering algorithm at the cost of few dB deterioration in PSR. The cluster centroid as tap weight reduces logic
used in FPGA for FIR filters to a great extent by reducing number of weight multipliers. Since kmeans
clustering is an iterativealgorithm, centroid for weights cluster is different in different iterations and causes
different clusters. This causes difference in clustering of weights and sometimes even it may happen that lesser
number of multiplier and lesser length of filter provide better PSR.
In this paper few sample optimum biphase codes have been provided in tabular form with their optimum
sidelobe supression filter (SSF) with optimum lengths and minimum multipliers to achieve low sidelobe level of
-35 dBto -40 dB and have been compared against PSR achieved without clustering.Clustering is used in FIR
filter for pulse compression and its effect is seen on peak to sidelobe ratio. This is being a genericmethod for
FIR filters to reduce number of multipliers can be extended to other similar applications.
PERFORMANCE EVALUATION OF ADAPTIVE ARRAY ANTENNAS IN COGNITIVE RELAY NETWORKcsijjournal
Adaptive Array Antennas (AAAs) are expected to play a key role in meeting the demands of the wireless communication systems of the future. AAAs in cognitive relay network is proposed to reduce the symbol error rate and improve the system performance. Many algorithms such as wiener solution and least mean square (LMS) will be explained to show how AAAs in cognitive relay network achieves this object. AAAs at different locations will be investigated under AWGN and Rayleigh fading channel. Moreover, enhancement the system performance by showing the effect of increasing the number of AAAs element at the relay node, increasing the source gain and decreasing the relay gain. In addition, increasing the rate adaptation and number of iterations in LMS algorithm has significant improvement in the system.
Multilevel inverters play a crucial part in the
areas of high and medium voltage applications. Among the three
main multilevel inverters used, the capacitor clamped multilevel
inverter(CCMLI) has advantage with respect to voltage
redundancies. This work proposes a switching pattern to improve
the performance of chosen H-bridge type CCMLI over
conventional CCMLI. The PWM technique used in this work is
Phase Opposition Disposition PWM(PODPWM). The
performance of proposed H-bridge type CCMLI is verified
through MATLAB-Simulink based simulation. It has been
observed that the THD is low in chosen CCMLI compared to
conventional CCMLI.
Optimization for Minimum Noise Figure of RF Low Noise Amplifier in 0.18µm Tec...IJEEE
Using a modified Cascode topology a 2GHz Low Noise Amplifier (LNA) has been implemented in Cadence Spectre RF tool on UMC 0.18µm technology to work under reduced power supply. After simulation it is found that at resonance frequency of 2GHz, the minimum noise figure is 2.5 dB and noise figure is 3 dB for a voltage gain of 17 dB.
In this paper, three beamforming design are considered for multi user MIMO system. First, transmit
beamformers are fixed and the receive (RX) beamformers are calculated. Transmit beamformer (TX-BF)is
projectedas a null space of appropriate channels. It reduces the interference for each user. Then the receiver
beamformer is determined which maximize the SNR. This beamforming design provides less computation time.
The second case is joint TX and RX beamformer for SNR maximization. In this transmitter and receiver
beamformer are calculated using extended alternating optimization (EAO) algorithm. The third one is joint
transmitter and receiver beamforming for SNR and SINR maximization using EAO algorithm. This algorithm
provides better error performance and sum rate performance. All the design cases are simulated by using
standard multipath channel model. Our simulation results illustrate that compared to the least square design and
zero forcing design, the joint TX and RX beamforming design using EAO algorithm provides faster
beamforming and improved error performance and sum rate.
A Low power discrete time sigma delta ADC consisting of a second order sigma delta modulator and third order Cascaded Integrated Comb (CIC) filter is proposed. The second order modulator is designed to work at a signal band of 20K Hz at an oversampling ratio of 64 with a sampling frequency of 2.56 MHz. It achieves a signal to noise ratio of 85.2dB and a resolution of 14 bits. The CIC digital filter is designed to implement a decimation factor of 64, operating at a maximum sampling frequency of 2.56 MHz. A second order sigma delta modulator is implemented in 0.18micron CMOS technology using full custom design and the third order digital CIC decimation filter is implemented in verilog HDL. The complete Sigma Delta ADC, consisting of analog block of second order modulator and digital block of decimator consumes a
total power 1.96mW.
Comparison of various noise mitigation technique used with clipping for reduc...eSAT Journals
Abstract
A simple technique used to reduce the PAPR of OFDM signals is to clip the signal to a maximum allowed value, at the cost of BER
degradation and out-of-band radiation. Clipping does not add extra information to the signal and high peaks occur with low
probability so the signal is seldom distorted. Out-of-band radiation can be reduced by filtering at the transmitter, the filter used in this
project consists on a FFT-IFFT pair which is easier to implement than traditional FIR filters and allows the implementation of the
clip & filter set several times in order to reduce the peak re growth that filtering introduces. The BER degradation can be mitigated by
reconstructing the signal at the receiver. We analyzed the performance of the decision-aided reconstruction (DAR) and improved DAR
(IDAR) techniques that iteratively try to guess the original symbols and proposed an improvement for one of those techniques.
Index Terms: Complementary cumulative distribution function (CCDF),high power amplifier (HPA), Orthogonal
Frequency Division Multiplexing (OFDM), Peak-to-Average Power Ratio (PAPR), inter-symbol interference (ISI)
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Wireless Communication Networks and Systems 1st Edition Beard Solutions Manualpuriryrap
Full download : http://alibabadownload.com/product/wireless-communication-networks-and-systems-1st-edition-beard-solutions-manual/
Wireless Communication Networks and Systems 1st Edition Beard Solutions Manual
Multilevel inverters play a crucial part in the
areas of high and medium voltage applications. Among the three
main multilevel inverters used, the capacitor clamped multilevel
inverter(CCMLI) has advantage with respect to voltage
redundancies. This work proposes a switching pattern to improve
the performance of chosen H-bridge type CCMLI over
conventional CCMLI. The PWM technique used in this work is
Phase Opposition Disposition PWM(PODPWM). The
performance of proposed H-bridge type CCMLI is verified
through MATLAB-Simulink based simulation. It has been
observed that the THD is low in chosen CCMLI compared to
conventional CCMLI.
Optimization for Minimum Noise Figure of RF Low Noise Amplifier in 0.18µm Tec...IJEEE
Using a modified Cascode topology a 2GHz Low Noise Amplifier (LNA) has been implemented in Cadence Spectre RF tool on UMC 0.18µm technology to work under reduced power supply. After simulation it is found that at resonance frequency of 2GHz, the minimum noise figure is 2.5 dB and noise figure is 3 dB for a voltage gain of 17 dB.
In this paper, three beamforming design are considered for multi user MIMO system. First, transmit
beamformers are fixed and the receive (RX) beamformers are calculated. Transmit beamformer (TX-BF)is
projectedas a null space of appropriate channels. It reduces the interference for each user. Then the receiver
beamformer is determined which maximize the SNR. This beamforming design provides less computation time.
The second case is joint TX and RX beamformer for SNR maximization. In this transmitter and receiver
beamformer are calculated using extended alternating optimization (EAO) algorithm. The third one is joint
transmitter and receiver beamforming for SNR and SINR maximization using EAO algorithm. This algorithm
provides better error performance and sum rate performance. All the design cases are simulated by using
standard multipath channel model. Our simulation results illustrate that compared to the least square design and
zero forcing design, the joint TX and RX beamforming design using EAO algorithm provides faster
beamforming and improved error performance and sum rate.
A Low power discrete time sigma delta ADC consisting of a second order sigma delta modulator and third order Cascaded Integrated Comb (CIC) filter is proposed. The second order modulator is designed to work at a signal band of 20K Hz at an oversampling ratio of 64 with a sampling frequency of 2.56 MHz. It achieves a signal to noise ratio of 85.2dB and a resolution of 14 bits. The CIC digital filter is designed to implement a decimation factor of 64, operating at a maximum sampling frequency of 2.56 MHz. A second order sigma delta modulator is implemented in 0.18micron CMOS technology using full custom design and the third order digital CIC decimation filter is implemented in verilog HDL. The complete Sigma Delta ADC, consisting of analog block of second order modulator and digital block of decimator consumes a
total power 1.96mW.
Comparison of various noise mitigation technique used with clipping for reduc...eSAT Journals
Abstract
A simple technique used to reduce the PAPR of OFDM signals is to clip the signal to a maximum allowed value, at the cost of BER
degradation and out-of-band radiation. Clipping does not add extra information to the signal and high peaks occur with low
probability so the signal is seldom distorted. Out-of-band radiation can be reduced by filtering at the transmitter, the filter used in this
project consists on a FFT-IFFT pair which is easier to implement than traditional FIR filters and allows the implementation of the
clip & filter set several times in order to reduce the peak re growth that filtering introduces. The BER degradation can be mitigated by
reconstructing the signal at the receiver. We analyzed the performance of the decision-aided reconstruction (DAR) and improved DAR
(IDAR) techniques that iteratively try to guess the original symbols and proposed an improvement for one of those techniques.
Index Terms: Complementary cumulative distribution function (CCDF),high power amplifier (HPA), Orthogonal
Frequency Division Multiplexing (OFDM), Peak-to-Average Power Ratio (PAPR), inter-symbol interference (ISI)
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
Wireless Communication Networks and Systems 1st Edition Beard Solutions Manualpuriryrap
Full download : http://alibabadownload.com/product/wireless-communication-networks-and-systems-1st-edition-beard-solutions-manual/
Wireless Communication Networks and Systems 1st Edition Beard Solutions Manual
A conceptual study of social entrepreneurshipdeshwal852
Social entrepreneurship is a unique entrepreneurship which is totally driven by the societal problems. Business entrepreneurship focuses on wealth creation and is of interest because of its potential to fuel economic development whereas social entrepreneurship focuses on ‘making the world a better place’ and creating social capital. Social entrepreneurs are driven by an ethical obligation and desire to improve their communities and societies. In this back drop an attempt is made to highlight the importance, ethics and preparation of young social entrepreneurs. All the relevant data was collected
through review of available literature.
DESIGN OF LOW POWER SAR ADC FOR ECG USING 45nm CMOS TECHNOLOGYVLSICS Design
Design of a low power Successive Approximation Register Analog to Digital Converter (SAR ADC) in 45nm CMOS Technology for biopotential acquisition systems is presented. It is designed by using a high threshold voltage (Vt) cell to reduce power dissipation. A 10-bit SAR ADC is designed and compared with the low resolution SAR ADC and normal threshold voltage (Vt) ADC with respect to power and delay. The results show that high Vt SAR ADC saves power upto 67% as compared to low Vt SAR ADC without any penalty of delay. Other performance metrics studied are the Effective Number of Bits (ENOB) and Signal to Noise Ratio (SNR), Signal to Noise and Distortion Ratio and Spurious Free Dynamic ratio.
DESIGN OF LOW POWER SAR ADC FOR ECG USING 45nm CMOS TECHNOLOGYVLSICS Design
Design of a low power Successive Approximation Register Analog to Digital Converter (SAR ADC) in
45nm CMOS Technology for biopotential acquisition systems is presented. It is designed by using a high
threshold voltage (Vt) cell to reduce power dissipation. A 10-bit SAR ADC is designed and compared with
the low resolution SAR ADC and normal threshold voltage (Vt) ADC with respect to power and delay. The
results show that high Vt SAR ADC saves power upto 67% as compared to low Vt SAR ADC without any
penalty of delay. Other performance metrics studied are the Effective Number of Bits (ENOB) and Signal to
Noise Ratio (SNR), Signal to Noise and Distortion Ratio and Spurious Free Dynamic ratio.
DESIGN OF IMPROVED RESISTOR LESS 45NM SWITCHED INVERTER SCHEME (SIS) ANALOG T...VLSICS Design
This work presents three different approaches which eliminates the resistor ladder completely and hence
reduce the power demand drastically of a Analog to Digital Converter. The first approach is Switched
Inverter Scheme (SIS) ADC; The test result obtained for it on 45nm technology indicates an offset error of
0.014 LSB. The full scale error is of -0.112LSB. The gain error is of 0.07 LSB, actual full scale range of
0.49V, worst case DNL & INL each of -0.3V. The power dissipation for the SIS ADC is 207.987 μwatts;
Power delay product (PDP) is 415.9 fWs, and the area is 1.89μm2. The second and third approaches are
clocked SIS ADC and Sleep transistor SIS ADC. Both of them show significant improvement in power
dissipation as 57.5% & 71% respectively. Whereas PDP is 229.7 fWs and area is 0.05 μm2 for Clocked SIS
ADC and 107.3 fWs & 1.94 μm2 for Sleep transistor SIS ADC.
PERFORMANCE EVALUATION OF ADAPTIVE ARRAY ANTENNAS IN COGNITIVE RELAY NETWORK csijjournal
Adaptive Array Antennas (AAAs) are expected to play a key role in meeting the demands of the wireless communication systems of the future. AAAs in cognitive relay network is proposed to reduce the symbol error rate and improve the system performance. Many algorithms such as wiener solution and least mean square (LMS) will be explained to show how AAAs in cognitive relay network achieves this object. AAAs at different locations will be investigated under AWGN and Rayleigh fading channel. Moreover, enhancement the system performance by showing the effect of increasing the number of AAAs element at the relay node, increasing the source gain and decreasing the relay gain. In addition, increasing the rate adaptation and number of iterations in LMS algorithm has significant improvement in the system.
Performance Evaluation Of Adaptive Array Antennas In Cognitive Relay Networkcsijjournal
Adaptive Array Antennas (AAAs) are expected to play a key role in meeting the demands of the wireless communication systems of the future. AAAs in cognitive relay network is proposed to reduce the symbol error rate and improve the system performance. Many algorithms such as wiener solution and least mean square (LMS) will be explained to show how AAAs in cognitive relay network achieves this object. AAAs
at different locations will be investigated under AWGN and Rayleigh fading channel. Moreover, enhancement the system performance by showing the effect of increasing the number of AAAs element at the relay node, increasing the source gain and decreasing the relay gain. In addition, increasing the rate adaptation and number of iterations in LMS algorithm has significant improvement in the system.
Performance Evaluation of Adaptive Array Antennas in Cognitive Relay Networkcsijjournal
Adaptive Array Antennas (AAAs) are expected to play a key role in meeting the demands of the wireless communication systems of the future. AAAs in cognitive relay network is proposed to reduce the symbol error rate and improve the system performance. Many algorithms such as wiener solution and least mean square (LMS) will be explained to show how AAAs in cognitive relay network achieves this object. AAAs at different locations will be investigated under AWGN and Rayleigh fading channel. Moreover, enhancement the system performance by showing the effect of increasing the number of AAAs element at
the relay node, increasing the source gain and decreasing the relay gain. In addition, increasing the rate adaptation and number of iterations in LMS algorithm has significant improvement in the system.
A Review: Compensation of Mismatches in Time Interleaved Analog to Digital Co...IJERA Editor
The execution of today's correspondence frameworks is exceedingly subject to the utilized Analog-to-Digital converters (ADCs), and with a specific end goal to give more flexibility and exactness to the developing correspondence innovations, superior-ADCs are needed. In this respect, the time-interleaved operation of an exhibit of ADCs (TI-ADC) might be a sensible result. A TI-ADC can build its throughput by utilizing M channel ADCs or sub converters in parallel and examining the data motion in a period-interleaved way. In any case, the execution of a TI-ADC gravely suffers from the bungles around the channel ADCs. In this paper we survey the advancement in the configuration of low-intricacy advanced remedy structures and calculations for time-interleaved ADCs in the course of the most recent five years. We devise a discrete-time model, state the outline issue, and finally infer the calculations and structures. Specifically, we examine proficient calculations to outline time-differing remedy filters and additionally iterative structures using polynomial based filters. Thusly, the remuneration structure may be utilized to repay time-differing recurrence reaction befuddles in time-interleaved ADCs, and in addition to remake uniform examples from nonuniformly tested indicators. We examine the recompense structure, research its execution, and exhibit requisition zones of the structure through various illustrations. At long last, we give a standpoint to future examination questions.
IJRET : International Journal of Research in Engineering and Technology is an international peer reviewed, online journal published by eSAT Publishing House for the enhancement of research in various disciplines of Engineering and Technology. The aim and scope of the journal is to provide an academic medium and an important reference for the advancement and dissemination of research results that support high-level learning, teaching and research in the fields of Engineering and Technology. We bring together Scientists, Academician, Field Engineers, Scholars and Students of related fields of Engineering and Technology.
SAF ANALYSES OF ANALOG AND MIXED SIGNAL VLSI CIRCUIT: DIGITAL TO ANALOG CONVE...VLSICS Design
Digital to analog converter is widely used mixed-signal circuit. Testing of analog and mixed signals faces
lots of challenges due to the wide range of circuits and unavailability of one appropriate fault model. SAF
(stuck_at_Fault), Stuck_open and stuck_short fault model at transistor level is used in this paper. Furtherthese fault models are used to analyze the effects on the
characteristics parameter of 3-bit R-2R DAC.
Duty Cycle Corrector Using Pulse Width ModulationVLSICS Design
In circuits, clocks usually play a very important role. Whenever data needs to be sampled, it is done with respect to clock signals. It uses the edges of the clock to sample the data. So, it becomes very much necessary to see to it that the clock signals are properly received specially in receiver circuits where data sampling is done, mainly in Double data rate(DDR) circuits. Due to effects such as jitter, skew, interference, device mismatches etc., duty cycle gets affected. We come up with duty cycle correctors that ensure 50% duty cycle of the clock signals. A duty cycle corrector (DCC) with analog feedback is proposed and simulated in 45nm process technology node. The duty cycle corrector operates for MHz frequency range covering the duty cycle from 35%-65%, with +/- 1.5% accuracy. The design is simple and the power consumption is 1.01mW.
International Journal of VLSI design & Communication Systems (VLSICS) VLSICS Design
In circuits, clocks usually play a very important role. Whenever data needs to be sampled, it is done with respect to clock signals. It uses the edges of the clock to sample the data. So, it becomes very much necessary to see to it that the clock signals are properly received specially in receiver circuits where data sampling is done, mainly in Double data rate(DDR) circuits. Due to effects such as jitter, skew, interference, device mismatches etc., duty cycle gets affected. We come up with duty cycle correctors that ensure 50% duty cycle of the clock signals. A duty cycle corrector (DCC) with analog feedback is proposed and simulated in 45nm process technology node. The duty cycle corrector operates for MHz frequency range covering the duty cycle from 35%-65%, with +/- 1.5% accuracy. The design is simple and the power consumption is 1.01mW.
DUTY CYCLE CORRECTOR USING PULSE WIDTH MODULATIONVLSICS Design
In circuits, clocks usually play a very important role. Whenever data needs to be sampled, it is done with
respect to clock signals. It uses the edges of the clock to sample the data. So, it becomes very much
necessary to see to it that the clock signals are properly received specially in receiver circuits where data
sampling is done, mainly in Double data rate(DDR) circuits. Due to effects such as jitter, skew,
interference, device mismatches etc., duty cycle gets affected. We come up with duty cycle correctors that
ensure 50% duty cycle of the clock signals. A duty cycle corrector (DCC) with analog feedback is proposed
and simulated in 45nm process technology node. The duty cycle corrector operates for MHz frequency
range covering the duty cycle from 35%-65%, with +/- 1.5% accuracy. The design is simple and the power
consumption is 1.01mW.
Novel Cyclic Prefix Selection to Improve Spectral Efficiency and Signal Stren...idescitation
The primary objective of using a guard interval in
form of Cyclic Prefix (CP) for WiMAX has always been to
mitigate the adverse effect of Inter Symbol Interference (ISI)
due to multipath fading. However, recent researches on
Adaptive Cyclic Prefix (ACP) have been suggested instead of
the existing fixed CP duration for changing Channel SNR.
These strategies provide a better Quality of Service (QoS)
and also enhances the performance of OFDM based WiMAX
systems. Based on these strategies, an “error on the fly”
correction based ACP has been proposed in this paper. The
proposed method, accompanied by exhaustive simulation
results, show its effectiveness by the improved Spectral
Efficiency (SE) and better Signal strength for a typical WiMAX
scenario under fast fading multipath channel conditions.
ESTIMATING PAPER IN VARIABLE GAIN RELAYING ON IMPERFECT CSIMichael George
Amplify and Forward (AF) relaying, which refers to simple amplification and forwarding of the information sent from a source to destination terminal. For the conventional three node Amplify and Forward (AF) relaying setup, investigate the effect of imperfect channel state information (CSI) at the relaying on the overall performance. In particular, consider variable gain AF relaying and derive expression for the outage and the error probability and expression for the complimentary cumulative distribution function (CCDF) of the peak-to-average power ratio (PAPR) at the relay is calculated. The proposed method was drawn from a performance analysis for outage CSI at the relay. Finally the project work was simulated using the MATLAB software.
DESIGN AND IMPLEMENTATION OF 10 BIT, 2MS/s SPLIT SAR ADC USING 0.18um CMOS TE...VLSICS Design
This paper focuses on Design and Implementation of 10 Bit, 2MS/s successive approximation Register (SAR) Analog to digital converter (ADC) using Split DAC architecture. This SAR ADC architecture is
designed and simulated using GPDK 0.18um CMOS technology. It consists of different blocks like sample
and hold, comparator, Successive Approximation Register (SAR) and Split Digital to analog converter(DAC). For each block of SAR ADC power is calculated. DAC is an important component within the SAR ADC. The charge redistribution DAC in a Split capacitor configuration has a total capacitance which is96.87% smaller compared to a conventional binary weighted design. Hence Split DAC gives an optimizedarchitecture and it consumes less power. Optimized design of DAC architecture ensures the accuracy ofthe components, which improves the performance of SAR ADC. Comparator constructed from resistances,capacitance and dependent voltage sources instead of MOS transistors. Dynamic range for SAR ADC
using split DAC is 60.19dB. The supply voltage is 1.2V. The total Power consumed by SAR ADC using
Split array DAC is 95.65114uW and SAR ADC using binary weighted capacitor DAC is 211.19084uW.
An approach to design Flash Analog to Digital Converter for High Speed and Lo...VLSICS Design
This paper proposes the Flash ADC design using Quantized Differential Comparator and fat tree encoder. This approach explores the use of a systematically incorporated input offset voltage in a differential amplifier for quantizing the reference voltages necessary for Flash ADC architectures, therefore eliminating the need for a passive resistor array for the purpose. This approach allows very small voltage comparison and complete elimination of resistor ladder circuit. The thermometer code-to-binary code encoder has become the bottleneck of the ultra-high speed flash ADCs. In this paper, the fat tree thermometer code to-binary code encoder is used for the ultra high speed flash ADCs. The simulation and the implementation results shows that the fat tree encoder performs the commonly used ROM encoder in terms of speed and power for the 6 bit CMOS flash ADC case. The speed is improved by almost a factor of 2 when using the fat tree encoder, which in fact demonstrates the fat tree encoder and it is an effective solution for the bottleneck problem in ultra-high speed ADCs.The design has been carried out for the 0.18um technology using CADENCE tool.
This is an overview of the Analog Devices’ JESD204 Interface Framework, a system-level software package targeted at simplifying development by providing a performance optimized IP framework.
An Introduction to ADI’s Power components used in RF signal chains, with special treatment of high performance data converters, transceivers and PLL/VCOs.
An Introduction to ADI’s RF Switches and RF Attenuators including their key characteristics and how and where they should be used in the RF signal chain.
Digital isolation plays a key role in designing industrial motor control systems. This presentation takes you through why, where and how for isolation designs that optimize system performance while meeting the ever stringent safety and efficient standards. Analog Devices, Nicola O'Byrne at PCIM 2015
Isolation in gate drive is one critical area for designing efficient, safe and highly productive motor control systems. Learn how the latest ADI isolated gate drives can help you solve the design challenges. Analog Devices, Dara O'Sullivan PCIM 2015
When it comes to high performance signal chains, you need high performance power solutions. Noise sensitive
circuits such as analog-to-digital converters (ADCs), digital-to-analog converters (DACs), amplifiers, and phase
lock loops (PLLs)—as well as FPGAs—demand low noise power supplies that require specialized design
techniques. Engineers spend hours trying to figure out how to power these circuits without adding noise.
This presentation will focus on understanding various methods for not only approaching but meeting system
requirements. The session will introduce tested solutions and layout considerations that must be taken into
account when designing with switching regulators and low drop out (LDO) regulators.
This session provides insight into the operation of electric motor drive systems. Topics include electric motor operation and construction, motor control strategies, feedback sensors and circuits, power and isolation, and challenges of designing highly efficient motor control systems. A new high performance servo control FMC board will be introduced in the presentation, which provides an efficient motor control solution for different types of electric motors, addresses power and isolation challenges, and provides accurate measurement of motor feedback signals and increased control flexibility due to FPGA interfacing capabilities. The motor control hardware platform will be used to demonstrate rapid prototyping of motor control algorithms using Xilinx base platforms and the MathWorks development and simulation tools.
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2. MS-2446 Technical Article
Page 2 of 5
BENEFITS OF INTERLEAVING
The benefits of interleaving span across multiple segments of
the market. The most desired benefit of interleaving is the
increased bandwidth made possible by the wider Nyquist
zone of the interleaved ADCs. Once again, taking the
example of two 100 MSPS ADCs interleaved to create a
sample rate of 200 MSPS, Figure 3 gives a representation of
the much wider bandwidth allowed by interleaving the two
ADCs. This creates advantages for many different applications.
As cellular standards increase channel bandwidth and the
number of operating bands, there are increased demands on
the available bandwidth in the ADC. In addition, in military
applications, the requirements for better spatial recognition,
as well as increased channel bandwidths in backend com-
munications require higher bandwidths from the ADC. Due
to the increased demands for bandwidth in these areas, there
is a need created to measure these signals accurately. Therefore,
measurement equipment has increased needs for higher
bandwidths in order to properly acquire and measure these
signals that have higher bandwidth. The system requirements
in many designs inherently stay ahead of commercial ADC
technology. Interleaving allows for some of this gap to be closed.
Figure 3. Two Interleaved ADCs—Nyquist Zone
The increased sample rate provides more bandwidth for
these applications but also allows for easier frequency
planning and reduction in the complexity and cost of the
anti-aliasing filter that is typically used at the ADC inputs.
With all these great benefits, one has to wonder what the
price is to pay. As with most things, there is no such thing as
a free lunch. Interleaved ADCs offer increased bandwidth
and other nice benefits, but there are some challenges that
arise when dealing with interleaved ADCs.
CHALLENGES WITH INTERLEAVING
There are some challenges and things to look out for when
interleaving ADCs. There are spurs that appear in the output
spectrum that result from the imperfections associated with
interleaving ADCs. These imperfections are basically
mismatches between the two ADCs that are being
interleaved. There are four basic mismatches that result in
spurs in the output spectrum. These are offset mismatch,
gain mismatch, timing mismatch, and bandwidth mismatch.
The easiest of these to understand is probably the offset
mismatch between the two ADCs. Each ADC will have an
associated dc offset value. When the two ADCs are interleaved
and samples are acquired alternatively back and forth between
the two ADCs, the dc offset of each successive sample is
changing. Figure 4 gives an example of how each ADC has
its own dc offset and how the interleaved output will effectively
switch back and forth between these two dc offset values.
The output switches between these offset values at a rate
of fS/2 which will result in a spur in the output spectrum
located at fS/2. Since the mismatch itself does not have a
frequency component and is only at dc, the frequency of the
spur that appears in the output spectrum only depends on
the sampling frequency and will always appear at a frequency
of fS/2. The magnitude of the spur is dependent upon the
magnitude of the offset mismatch between the ADCs. The
greater the mismatch, the larger the spur will be. In order to
minimize the spur caused by the offset mismatch, it is not
necessary to completely null the dc offset in each ADC.
Doing this would filter out any DC content in the signal and
would not work for systems using a ZIF (zero IF) architecture
where the signal content is real and complex and includes
data at DC. Instead, a more appropriate technique would be
to match the offset of one of the ADCs to the other ADC.
The offset of one ADC is chosen as the reference, and the
offset of the other ADC is set to match that value as closely
as possible. The better matched the offset values are, the
lower the resulting spur is at fS/2.
The second mismatch to look at when interleaving is
the gain mismatch between the ADCs. Figure 5 gives a
representation of the gain mismatch between two interleaved
converters. In this case, there is a frequency component to
the mismatch. In order to observe this mismatch, there has
to be a signal applied to the ADCs. In the case of the offset
mismatch, no signal is necessary to see the inherent dc offset
of the two ADCs. In the case of the gain mismatch, there is
no way to see the gain mismatch unless a signal is present
and the gain mismatch can be measured. The gain mismatch
will result in a spur in the output spectrum that is related to
the input frequency, as well as the sampling rate, and will
appear at fS/2 ± fIN. In order to minimize the spur caused by
3. Technical Article MS-2446
Page 3 of 5
the gain mismatch, a similar strategy as what is used for the
offset mismatch is employed. The gain of one of the ADCs is
chosen as the reference, and the gain of the other ADC is set
to match that gain value as closely as possible. The better the
gain values of each ADC are matched to each other, the less
the resulting spur will be in the output spectrum.
Next, we must examine the timing mismatch between the
two ADCs. The timing mismatch has two components,
group delay in the analog section of the ADC and clock
skew. The analog circuitry within the ADC has an associated
group delay and the value can be different between the two
ADCs. In addition, there is clock skew that has an aperture
uncertainty component in each of the ADCs and has a
component related to the accuracy of the clock phases
that are input to each converter. Figure 6 gives a visual
representation of the mechanism and effects of the timing
mismatches in the ADCs. Similar to the gain mismatch spur,
the timing mismatch spur is also a function of the input
frequency and the sample rate and appears at fS/2 ± fIN.
In order to minimize the resulting spur, the group delay
through the analog section of each converter needs to be
properly matched with good circuit design techniques. In
addition, the clock path designs need to be closely matched
to minimize aperture uncertainty differences. And lastly, the
clock phase relationships need to be precisely controlled
such that the two input clocks are as close to 180° apart as
possible. As with the other mismatches, the goal is to
attempt to minimize the mechanisms that cause the timing
mismatch.
The last mismatch to look at is probably the most difficult to
comprehend and handle; it is the bandwidth mismatch. As
shown in Figure 7, the bandwidth mismatch has a gain and a
phase/frequency component. This makes bandwidth mismatch
more difficult because it contains components from two of
the other mismatch parameters. In the bandwidth mismatch,
however, we see different gain values at different frequencies.
In addition, the bandwidth has a timing component which
causes signals at different frequencies to have different
delays through each converter. The best way to minimize
the bandwidth mismatch is to have very good circuit design
and layout practices that work to minimize the bandwidth
mismatches between the ADCs. The better matched each
ADC is, the less the resulting spur will be. Just as the gain
and timing mismatches caused spurs in the output spectrum
at fS/2 ± fIN, the bandwidth mismatch also results in a spur at
the same frequency.
Figure 4. Offset Mismatch
Figure 5. Gain Mismatch
4. MS-2446 Technical Article
Page 4 of 5
Figure 6. Timing Mismatch
Figure 7. Bandwidth Mismatch
Now that we’ve discussed four different mismatches that
cause issues when interleaving ADCs, it is apparent that a
commonality has emerged. Three of the four mismatches
produce a spur in the output spectrum at fS/2 ± fIN. The
offset mismatch spur can be easily identified since it alone
resides at fS/2 and can be compensated fairly easily. The gain,
timing, and bandwidth mismatches all produce a spur at
fS/2 ± fIN in the output spectrum so the question is how to
identify the contribution of each. Figure 8 gives a quick
visual guide to the process of identifying the sources of the
spurs from the different mismatches of interleaved ADCs.
Figure 8. Interrelated Nature of Interleaving Mismatches
If looking purely at gain mismatch alone, it is a low
frequency, or dc, type of mismatch. The gain component
of the bandwidth mismatch can be separated from the gain
mismatch by performing a gain measurement at low
frequency near dc and then performing gain measurements
at higher frequencies. The gain mismatch is not a function
of frequency like the gain component of the bandwidth
mismatch. A similar approach is used for the timing mismatch.
A measurement is performed at low frequency near dc and
then subsequent measurements are performed at higher
frequencies to separate the timing component of bandwidth
mismatch from the timing mismatch.
CONCLUSION
The newest communication system designs, cutting edge
radar technologies, and ultrahigh bandwidth measurement
equipment seem to constantly outpace the available ADC
technology. These requirements push both users and
manufacturers of ADCs to develop methods to keep pace
with these demands. Interleaving ADCs allows for greater
bandwidths to be achieved at a faster pace than the traditional
path of increasing the conversion rate of a typical ADC. By
taking two or more ADCs and interleaving them together,
the available bandwidth is increased, and system design
requirements can be met at a faster pace. Interleaving ADCs
does not come for free, however, and mismatches between
the ADCs cannot be ignored. Even though the mismatches
do exist, knowing about them and how to appropriately deal
with them can enable designers to use these interleaved ADCs
more intelligently and meet the ever increasing demands of
their latest system designs.