This document discusses techniques for improving power supply rejection ratio (PSRR) and common mode rejection ratio (CMRR) in fully differential amplifiers. It describes how external components like mismatched gain-setting resistors can degrade PSRR and CMRR performance. The role of the bypass capacitor in improving PSRR is explained, with up to a 20dB improvement when a 0.1-1uF capacitor is used. Finally, layout techniques like symmetrical component placement and minimizing trace lengths are recommended to boost CMRR and PSRR.
How to Identify and Prevent ESD Failures using PathFinderAnsys
This presentation provides an introduction to common ESD failure mechanism in today's ICs and the challenges in addressing them. It will highlight PathFinder, a layout based ESD integrity analysis platform with an integrated modeling, extraction and simulation environment that enables IC designers perform exhaustive verification of all ESD discharge pathways at the IP and full-chip level. It will also share case study of some real life ESD failure scenarios and how PathFinder was used to root-cause them. It reviews the list of ESD checks that can be performed from early floor planning to final sign-off for ESD robustness and ESD failure prevention. Learn more on our website: https://bit.ly/1vRDycB
Design of ESD protection for high-speed interfacesSofics
Semiconductor companies are developing ever faster wireless, wired and optical interfaces to satisfy the need for higher data throughputs. They rely on BiCMOS, advanced CMOS and FinFET nodes with ESD-sensitive circuits. However, the parasitic capacitance of the traditional ESD solutions limits the signal frequency. This paper demonstrates small area and low-cap Analog I/Os used in TSMC 28nm CMOS and TSMC 16nm, 12nm, 7nm FinFET technologies for high speed SerDes (28Gbps to 112Gbps) circuits. Parasitic capacitance of the ESD solutions is reduced below 100fF and for some silicon photonics applications even below 20fF.
2020 04 sofics low cap esd
Not many customers know that we offer full PCB design and layout services here at Epec. Design and layout may not be a full-time employable position, so there are advantages of having your PCB fabricator complete the PCB design for you, not to mention the time needed to accomplish this task. So, rely on Epec to be an extension of your electrical engineering team.
PCB designs can be difficult to manufacture. Working in tandem with your circuit board supplier is beneficial to both you and your supplier. It can save cost, reduce manufacturing challenges and prototyping.
Knowing what is needed for quoting purpose and at the time of your order is key to a smooth process.
In this webinar, we review what is needed in terms of the Bill of Materials and schematic details to accurately quote and deliver the exact PCB design and layout that you require.
For more information on our custom PCB solutions, visit https://www.epectec.com/pcb/
How to Identify and Prevent ESD Failures using PathFinderAnsys
This presentation provides an introduction to common ESD failure mechanism in today's ICs and the challenges in addressing them. It will highlight PathFinder, a layout based ESD integrity analysis platform with an integrated modeling, extraction and simulation environment that enables IC designers perform exhaustive verification of all ESD discharge pathways at the IP and full-chip level. It will also share case study of some real life ESD failure scenarios and how PathFinder was used to root-cause them. It reviews the list of ESD checks that can be performed from early floor planning to final sign-off for ESD robustness and ESD failure prevention. Learn more on our website: https://bit.ly/1vRDycB
Design of ESD protection for high-speed interfacesSofics
Semiconductor companies are developing ever faster wireless, wired and optical interfaces to satisfy the need for higher data throughputs. They rely on BiCMOS, advanced CMOS and FinFET nodes with ESD-sensitive circuits. However, the parasitic capacitance of the traditional ESD solutions limits the signal frequency. This paper demonstrates small area and low-cap Analog I/Os used in TSMC 28nm CMOS and TSMC 16nm, 12nm, 7nm FinFET technologies for high speed SerDes (28Gbps to 112Gbps) circuits. Parasitic capacitance of the ESD solutions is reduced below 100fF and for some silicon photonics applications even below 20fF.
2020 04 sofics low cap esd
Not many customers know that we offer full PCB design and layout services here at Epec. Design and layout may not be a full-time employable position, so there are advantages of having your PCB fabricator complete the PCB design for you, not to mention the time needed to accomplish this task. So, rely on Epec to be an extension of your electrical engineering team.
PCB designs can be difficult to manufacture. Working in tandem with your circuit board supplier is beneficial to both you and your supplier. It can save cost, reduce manufacturing challenges and prototyping.
Knowing what is needed for quoting purpose and at the time of your order is key to a smooth process.
In this webinar, we review what is needed in terms of the Bill of Materials and schematic details to accurately quote and deliver the exact PCB design and layout that you require.
For more information on our custom PCB solutions, visit https://www.epectec.com/pcb/
�The sample calculations shown here illustrate steps involved in calculating the relay settings for generator protection.
�Other methodologies and techniques may be applied to calculate relay settings based on specific applications.
Verilog codes and testbench codes for basic digital electronic circuits. shobhan pujari
Verilog codes and test bench codes for full adder,full adder using 2 half adders,Ripple carry adder,16x1 mux using 4x1 mux,decoder,mealy state machine,counter. These are more useful for bachelor students and masters students who are pursuing degree in electrical engineering .
CAN Simulation is extremely useful at the time of development and testing automotive components before mass production. It also allows cost reduction by reducing shipment of multiple parts to different software houses at the time of development. This presentation allows you to understand the effectiveness in building a low cost can simulator.
Picor, a Vicor company located in North Smithfield, Rhode Island, provides highly integrated, silicon-centric power conversion and power management solutions. Picor's silicon-centric productss complement Vicor's power technology and adhere to Vicor core strategy of innovation and performance.
�The sample calculations shown here illustrate steps involved in calculating the relay settings for generator protection.
�Other methodologies and techniques may be applied to calculate relay settings based on specific applications.
Verilog codes and testbench codes for basic digital electronic circuits. shobhan pujari
Verilog codes and test bench codes for full adder,full adder using 2 half adders,Ripple carry adder,16x1 mux using 4x1 mux,decoder,mealy state machine,counter. These are more useful for bachelor students and masters students who are pursuing degree in electrical engineering .
CAN Simulation is extremely useful at the time of development and testing automotive components before mass production. It also allows cost reduction by reducing shipment of multiple parts to different software houses at the time of development. This presentation allows you to understand the effectiveness in building a low cost can simulator.
Picor, a Vicor company located in North Smithfield, Rhode Island, provides highly integrated, silicon-centric power conversion and power management solutions. Picor's silicon-centric productss complement Vicor's power technology and adhere to Vicor core strategy of innovation and performance.
A 10 d bm 25 dbm, 0.363 mm2 two stage 130 nm rf cmos power amplifierVLSICS Design
This paper proposes a 2.4 GHz RF CMOS Power amplifi
er and variation in its main performance
parameters i.e, output power, S-parameters and powe
r added efficiency with respect to change in supply
voltage and size of the power stage transistor. The
supply voltage was varied form 1 V to 5 V and the
range
of output power at 1dB compression point was found
to be from 10.684 dBm to 25.08 dBm respectively.
The range of PAE is 16.65 % to 48.46 %. The width o
f the power stage transistor was varied from 150 μm
to 500 μm to achieve output power of range 15.47 dB
m to 20.338 dBm. The range of PAE obtained here is
29.085 % to 45.439 %. The total dimension of the la
yout comes out to be 0.714 * 0.508 mm
2
.
Series op-amp regulator – IC voltage regulator – Switching regulator – Digital to analog converters–specifications–weighted resistor type– R-2R ladder type-Analog to digital converter –specifications–counter ramp, flash, successive approximation, dual slope types-Voltage to frequency converter–Frequency to voltage converter– Analog multiplier
International Refereed Journal of Engineering and Science (IRJES)irjes
International Refereed Journal of Engineering and Science (IRJES) is a leading international journal for publication of new ideas, the state of the art research results and fundamental advances in all aspects of Engineering and Science. IRJES is a open access, peer reviewed international journal with a primary objective to provide the academic community and industry for the submission of half of original research and applications.
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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
Design of Low Power & High Speed Comparator with 0.18μm Technology for ADC Ap...IJERA Editor
In Analog to Digital Converter (ADC), high speed comparator influences the overall performance of ADC directly. This paper presents the high speed & low power design of a CMOS comparator. Schematic design of this comparator is fabricated in a 0.18μm UMC Technology with 1.8V power supply and simulated in cadence Virtuoso. Simulation results are presented and it shows that this design can work under high speed of 0.8108 GHz. The design has a low offset voltage, low power dissipation 108.0318μw. In addition we have verified present results with schematic view design and also compared these results with earlier reported work and got improvement in this reported work.
Block diagram of a typical op-amp – characteristics of ideal and practical op-amp - parameters of opamp – inverting and non-inverting amplifier configurations - frequency response - circuit stability.
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CFD analysis is incredibly effective at solving mysteries and improving the performance of complex systems!
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It is always satisfying when we can help solve complex challenges like this. Do your systems also need a check-up or optimization? Give us a call!
Work done in cooperation with James Malloy and David Moelling from Tetra Engineering.
More examples of our work https://www.r-r-consult.dk/en/cases-en/
Cosmetic shop management system project report.pdfKamal Acharya
Buying new cosmetic products is difficult. It can even be scary for those who have sensitive skin and are prone to skin trouble. The information needed to alleviate this problem is on the back of each product, but it's thought to interpret those ingredient lists unless you have a background in chemistry.
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The automated cosmetic shop management system should deal with the automation of general workflow and administration process of the shop. The main processes of the system focus on customer's request where the system is able to search the most appropriate products and deliver it to the customers. It should help the employees to quickly identify the list of cosmetic product that have reached the minimum quantity and also keep a track of expired date for each cosmetic product. It should help the employees to find the rack number in which the product is placed.It is also Faster and more efficient way.
Welcome to WIPAC Monthly the magazine brought to you by the LinkedIn Group Water Industry Process Automation & Control.
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2. Application Information
MEASURING POWER SUPPLY REJECTION RATIO
(PSRR)
The type of PSRR we are interested in here is an AC
specification measuring the ability of the amplifier to reject
AC-ripple voltage on the power supply bus, as opposed to a
DC specification where we measure the change in output
voltage for a change in supply voltage. Basically, ripple
PSRR is the ratio of the differential output voltage to the
supply ripple voltage expressed in dB as shown in Equation
1.
(1)
A test circuit for measuring PSRR is shown in Figure 2. The
amplifier’s AC inputs are terminated to GND with a low value
resistor—typically 10Ω. The value of the input capacitors
Ci1 and Ci2 should be matched as closely as possible. Any
mismatch can compromise PSRR performance at low fre-
quencies. An alternate solution is the elimination of input
coupling capacitors terminating the inputs directly to GND. A
low-level AC voltage, in the range of 100mVpp to 500mVpp
is combined with VDD. This AC plus DC signal is applied to
the amplifier’s VDD pin. Any residual AC signal at the ripple
frequency present across the BTL outputs is a function of the
amplifier’s PSRR. The magnitude of this residual signal is
measured with an FFT (using a spectrum analyzer or Audio
Precision instrument). Using Equation 1 gives the PSRR
value in dB.
MEASURING COMMON MODE REJECTION RATIO
(CMRR)
Common Mode Rejection Ratio is an ability of the differential
amplifier to reject common mode input signal and is ex-
pressed in dB as shown in Equation 2.
(2)
A test circuit for measuring CMRR is shown is Figure 3. The
amplifier’s AC inputs are connected to a common-mode AC
input. Output can be measured by using a high precision AC
Volt Meter or Audio Precision instrument. Equation 2 gives
the CMRR measurement in dB. For differential input ampli-
fiers with external gain-settings resistors, CMRR measure-
ment is highly dependent on external resistors as well as
board layout. This will be fully discussed in the next section.
As a side note, a lot of newer audio measuring instruments
such as Audio Precision can perform the CMRR test (and a
lot of other audio parameters as well) automatically.
20182533
FIGURE 2. PSRR Measurement Test Circuit
AN-1447
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3. Application Information (Continued)
EFFECTS OF EXTERNAL GAIN RESISTORS
It is extremely important to match the input resistors to each
other as well as the feedback resistors to each other for best
CMRR performance. When the inputs of the fully differential
amplifier are DC-coupled, resistor matching differences gen-
erate net DC currents across the load because of the bal-
anced nature of the differential amplifiers.
Internally these amplifiers consist of two circuits: a differen-
tial amplifier and a common-mode feedback amplifier that
adjusts the output voltages so that the nominal DC output
bias remains VDD/2. Assuming that the amplifier’ has two
equal “halves.” Equation 3 can be obtained by the simple
analysis of the differential amplifier in Figure 1 with Vcmi =
0V. Each half uses an input and feedback resistor (Ri and Rf)
and contributes to each side of the equation. This equation
shows an output offset DC voltage that can result because of
resistor mismatching either between feedback resistors (Rf1
and Rf2) or input resistors (Ri1 and Ri2).
(3)
Ideally, when Ri1 = Ri2 and Rf1 = Rf2, we get perfectly
matched and balanced input and feedback resistors pairs
and no offset voltage. But if, for example, we assume:
Ri1 = Ri2 = R
Rf1 = 0.8R and Rf2 = 1.2R, with 20% tolerance in the
feedback resistors.
We will get an offset voltage of about 0.45 Volts and load
current of about 46mA assuming an 8Ω load connected
across the output. Now that’s quite a big DC offset voltage!
As a result, this reduces the battery life and could affect the
speaker performance significantly because of extra DC cur-
rent flowing through the voice coil. Common Mode Rejection
Ratio is a parameter that can be gravely affected by mis-
matched gain resistors. A graph of Common Mode Rejection
Ratio vs. feedback resistor mismatch is shown in Figure 4.
As can be seen in the graph, a feedback resistor mismatch
of 0.4 reduces the CMMR approximately 23dB from the ideal
condition perfectly matched resistor.
PSRR is also affected by the gain resistors mismatch, but
with a small capacitor on the bypass pin this effect is re-
duced extensively and yields practically no effect at all on the
power supply rejection. The effects of bypass capacitor will
be fully discussed in the next section. Thus, for all practical
purpose, resistors of 1% tolerance or even better should be
used for optimal performance and best common mode re-
jection ratio.
20182507
FIGURE 3. CMRR Measurement Test Circuit
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3
4. Application Information (Continued)
EFFECTS OF BYPASS CAPACITOR
Fully differential amplifiers offer an “optional” bypass capaci-
tor (CB) and allow a designer to use these amplifiers with
minimal component count. Before eliminating the optional
bypass capacitor to reduce component count, one should
understand how that might affect the overall performance of
the amplifier. Internally, a common mode amplifier adjusts
the two outputs to a quiescent DC voltage equal to halve-
VDD. Any supply fluctuations cause both outputs to move in
phase. This ideally creates a net change of 0VDC differen-
tially across the outputs. Thus, a bypass capacitor is not
really required and can be considered optional. But in the
real world, these amplifiers are not perfect. Furthermore,
mismatch in the external resistors can result in unbalanced
amplifier operation. PSRR is the most important parameter
that would be affected significantly by eliminating the bypass
capacitor.
Differential input amplifiers are considered excellent low
noise and high PSRR amplifiers when compared to similar
single-ended amplifiers. As shown in Figure 5 at low ripple
frequencies, the PSRR is close to 70dB, even without a
bypass capacitor. However, using a bypass capacitor in
range of 0.1 uF to 1 uF offers a significant 20dB PSRR
improvement. Depending upon the application, PSRR of
70dB might be considered good and more than adequate for
most applications. However, in cell-phone market where an
excellent PSRR is desired, particularly at lower frequencies,
20182535
FIGURE 4. CMRR vs Feedback Resistor Mismatch
20182536
FIGURE 5. PSRR vs Ripple Frequency
AN-1447
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5. Application Information (Continued)
adding a bypass capacitor certainly will improve the lower
frequencies power supply rejection. Furthermore, the ampli-
fier will be less sensitive to slight gain resistor value mis-
match.
LAYOUT CONSIDERATIONS
Printed circuit board layout is generally considered to be
very application specific. Nevertheless, it is possible to ob-
serve some guidelines that optimize the overall performance
of the amplifier. Fully differential amplifiers come in different
packages.
Please contact the National Semiconductor Corp. website
for package-specific applications information before attempt-
ing to start any new layout. Another important factor to
consider is star ground vs. ground plane. This is very appli-
cation and package specific. Either configuration is used
when combined with the following general suggestions:
a) Make use of symmetrical placement of components (i.e.
feedback resistors and input resistors).
b) If not using ground planes, VDD and GND traces should
be as wide as possible.
c) If a heat-sink plane is desired for exposed-DAP pack-
ages, it should be appropriately sized. Refer to the power
derating graphs in the corresponding datasheet.
d) The distance between the chip and any possible antenna
source should be as far as possible.
e) If possible, make the output traces short and equal in
length and away from the any antenna source.
f) If using a star ground, all the GNDs such as bypass
capacitor GND, supply capacitor GNDs, and any other sys-
tem ground should be directly connected to a single point on
the board, possibly at the board’s point of entry for the power
supply GND.
AN-1447
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5
6. Revision Table
Rev Date Description
1.0 04/20/06 Initial release.
1.1 07/24/06 Simple text edits, then re-released the App Notes into the WEB.
National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves
the right at any time without notice to change said circuitry and specifications.
For the most current product information visit us at www.national.com.
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AN-1447
Improving
PSRR
and
CMRR
in
Fully
Differential
Amplifiers