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86 Threads found on Differential Pair Design
This function can be realized with "differential pair" circuit.There are many information about this circuit and Barrie Gilbert ( Analog Guru ) has developed tons of circuits using with this basic one. If you search the articles of this great man and Chris Toumazou, you'll find very interesting and chic ideas.
135454 135455 1)Most opamp use nmos differential amp, but this one uses pmos. why? nmos is faster. 2)the third stage, buffer stage gain, and on the circuit, it shows 2 pmos(m8, m9). why? isn't it inverter is used as buffer? how's 2 pmos is a buffer?
Can any one help me in Understanding the OTA design attached in the picture below. I want to know the purpose of MC, MCN and MCP. I can understand MBN is for biasing but whats the purpose of MBP than? please anyone explain in detail. Thanx
Well the design constraints are the noise, speed, offset and power dissipation. For high speed, you will need minimum length transistors. The noise is mostly dominated by the input differential pair. So you have to do a PNOISE sim and keep increasing the width of input diff pair till you achieve your target. Similar exercise (...)
Why common centroid technique preferred for differential pair..? if you say it eliminates linear gradients then 1. Please explain what are the linear gradients and which type of mismatch category will it fall..(random/systematic).. 2. How exactly is this common centroid fighting against these linear gradients..? 3. If you can... please stick to
Dear all! I'm trying to amplify a differential signal what may vary from a few hundreds of micro-volts to tens of milli-volts. The main challenge is to design this amp in sub 1V and in sub 1?A. I designed OpAmp but won't work with such a low input voltage. The only way I found is to amplify separately these two (...)
How do you do load pull on a differential pair to know the optimum load impedance for the transistor? Do you just use one single transistor instead? A real design (either IC or discrete) will have some coupling between both output transistors, also a non-zero power supply impedance. So the impedance of the differential (...)
The long tailed pair is the basis for differnetial amplifier and its first stage. I have usually seen it constructed using pair of NPN transistors in common emitter configuration with their emitters feeding into a single emitter resistor. The common mode rejection ratio of this can be improved by connecting a current sink made using NPN at the emit
Hi, I already design a LNA schematic and layout, so far so good. Now, I plan to make it as a differential pair LNA... I had some idea about the schematic and test bench, but it does not work very good specially when it comes to layout. Can anybody introduce me the references I can use for finding the structure os schematic and also the (...)
Read the design guidelines RS-485 compliant drivers can be used for Rs-422 multidrop with one driver. THe termination resistors at each end of the bus match the differential impedance of the pair with active terminators ( ie. pull up/down or series to Vth
I'm routing a 4 layer board with a USB2.0 differential pair. The application note has an example stackup for a 4 layer FR-4 board as shown below (top image). The example includes trace width and spacing for a 90Ω differential pair. When I enter these parameters into either of the calculators I have, they both give (...)
I would be looking at folded cascode and using HV devices (like LDMOS) in the diff pair and the cascode guards. That will let you "pin" most of the critical voltages that have to slide across supply-driven and common-mode-driven ranges. But you need to be wary of input differential voltage max specs (which might force you to use thick gate MOS dev
Hi All, I am designing a two stage miller opamp (pmos input differential pair) in subthreshold region. I am using 32nm technology node. The parameters are given below: 1. Supply voltage = 1V 2. Bias Current = 200nA 3. Transistor Length = 160nm=(5 Lmin) There are no specific requirements but I have to just reduce power dissipation. I am (...)
Hi guys. I have to design the layout of the above mentioned ota. I am thinking on how layout the ota AMP. This OTA has PMOS input transistor. What I was thinking to do was to follow the schematic. That is: Interdigitize the cascode transistores that bias the diff. pair. Interdgtz the differential pair. (...)
Hello, I want to design a USB connection from a chip to a pcie header. The problem is the differential pins of header is in the opposite direction of that of chip. So I have to create a via and change the direction of one line to another layer in order to connect the two pins. The topology of the components cannot be changed. So I have to do so
Dear all, I tried to design a transmission line transformer as in attached image using differential pair, Can any one help me ,please? Thanks in advance,
Hi, To desiogn an op-Amp you must design proper biasing ciruits which is essential for the proper operation... For current mirror you have to find appropriate length which makes good mirroring of current... And it depends on which technology you are using.... Then choose somewhat bigger area for the differential input pair of the Op-Amp , (...)
Hi everyone, In my design, I have some special pairs of wires. The two signals in each pair should be totally matching with each other, having the same transmission delay like "differential signals". Is there any commands that I could use as timing constraint or routing options in Encounter? Thanks
Hello, Please I want to ask how to design an amplifier " transconductance Gm" with high Gm of 30m and high output resistance of 100K at the same time , I used folded casocde amplifier to satisfy high output resistance but because it was designed to be with high Gm , the current in the differential pair transiator and (...)
Hi All, I am designing an amplifier for extra-cellular neural recording. The input is given to a OSFET differential pair (M1 and M2 - input transistors). All the materials above the gate-oxide of the OSFET sensor is removed and exposed to the buffer solution where the neuron is kept. The gate voltage is set by using an electrode immersed (...)
Hi All, In my design I have assigned 82 differential pairs. Each signal should be match with their differential signal. So I need to manual report for each pair. Let me know any high speed rule setting for 1 mil DRC length tolerance or any script can we run for this. If so, kindly reply me. Thanks, (...)
hi.I am a beginner and I need to design unipolar c-mos op amp with 5 volts supply and i have no idea how to start :(.I know op amp have i/p stage having differential pair and common source as output stage for low Ro, also transistors used in design must be original transistor like (for eg 2n7000 ) so what should be the (...)
Hello All, In my design i am using differential pair and i have set all the rules required for the differential pair routing like clearance, matched net lengths, differential pair routing and differential width. Everything is working fine but matched (...)
Hi!, We have just designed a 2 stage OTA with a cascoded differential pair as the first stage and a common source amplifier as the second stage. The gain is 59.3dB and we need to measure the slew rate. Can anyone please tell me how to go about measuring the slew rate? The method that we were using is to supply a 1Vpp pulse at the input (...)
Hi i have a doubt in designing differential amplifier, generally we will be designing the W/L ratio of diff amplifier in large, what is the reason behind this.... what happens if we increase the length in pmos diff amplifier? Operating at large W/L pushes the diff pair towards weaker inversion which is the OP region of
Hi, pls anyone help me how to increase ICMR for fully differential telescopic opamp(PMOS differential pair). i got the range from 742.8mv to 973.7mv.
A carefully designed differential pair with buffer output stage will convert your diff. signal to single ended.
You should take the specified differential impedance of 90 ohm +/- 15% simply as a fact. Asking "why is it so" is a question of technical history. I guess, that the designers of the USB standard found 90 ohm more easily to achieve with a shielded twisted pair. USB uses both single ended and differential signaling by (...)
Hello - this is my first post here. I need to design a suitable voltage-controlled current source to drive a 4x transistor differential amp (long-tail pair) - like this: Wikipedia: Long-tailed-pair I've never used a transistor diff-amp before so this is just for testing and proof
hi friends, i just have a project that i should design an op-amp with 80 db gain, +5 to -5v supply and up to 10bipolar transistor and maximum 5 mw power dissipation. i will be wondering if you could help me? special thanks in advance.... i also use a differential pair with a gain stage and a class b output stage, but no results.
in dynamic comparator design of differential pair, i have some questions here. 65665fig1 is the schematic, fig2 is the design equation. d=ID5/ID6, e=Vin/Vref, W1=W2, W3=W4. but how to decide the value of ID5, ID6, d? because M5 and M6 are controled by clock signal Vclock, so the current of M5, M6 is difficult to set
Hi All, I am new to this membership. i am very glad to see the comments in this website. I too have some doubts, kindly give comments. I am using ARES PCB designer, when I try to route a differential pair there was no option I noticed. Is it possible to do differential pair routing in ARES PCB (...)
Which design system? Which design kit? Which model file(s)? two stage differential pair: which properties?
In my design of differential amplier, I use two 40u/8u MOS transistor as the differential pair. And my process is 0.35um BCD. Then ,can I know how many percentage does the matching of input MOS transistor can achieve? ---------- Post added at 16:15 ---------- Previous post was at 16:09 ---------- Can it
The classical text book Gray, Hurst, Lewis and Meyer, Analysis and design of Analog Integrated Circuits discusses the building blocks of operational amplifiers (differential pair, current mirrors, output stages) and compensation schemes in detail. The present circuit isn't actually an OP amp rather than a single ended amplifier, partly AC co
My problem is that the output of the differential pair is saturated What do you mean with this?Transistors fall into linear region? Explain further...or show a transient plot. Did you check the biases in the whole circuit and are correct at the desired point?The desired point is determined by your specifications.
hi all, I am trying to design a differential comparator in which i have a differential input stage, then two cmos flip differential amplifier is actually having a differential PMOS input pair biased by PMOS current mirror of the ratio of 1:2 and its directly connected to the flip flop (...)
Dear All, I need to design a simple single-ended differential input pair OTA for gm-C filter. Here the Gm-block should operate in open-loop configuration. So if there is no negative dc feedback how can I ensure the output common-mode level. To provide only DC-feedback, I need to use large resistor and large capacitor which is not (...)
I am trying to design an op-amp with rail to rail inputs and am finding an issue with the symmetric input stage trick. I am limited to a process with no floating gate and nothing fancy like triple well. I have tried two approaches, one with a simple dual (symmetric) nmos and pmos differential pair and also with a dual folded cascode (...)
hi i feel there are 2- mistakes in the design 1) ur output stage is nmos is current source & Pmos as amplifier... this leads to large offset... u have to chenge it to Nmos as amplifier & Pmos as current source 2) the is a cap (i cant figure out the value) between drains of input differential pair NMOS transistors..instead u have (...)
in gilbert mixer, how to design for low intermodulation product? should i add source resistor to the differential pair driven by RF input to increase the linearity? ---------- Post added at 15:35 ---------- Previous post was at 15:16 ---------- In mixer products, usually ip3 is specified. why is that?
A CMOS differential pair with current source and then Source follower with current source will serve you.. differential pair will have high input impedance that wil not load your VCO, Source follower wil have low output impedance to drive low loads.
I need your help in length tuning a group of nets! design is a DDR2 board, I am trying to tune each DQS group. Each group contain an 8-bit single ended data lines and a differential pair. Interactive routing and length tuning of single ended section is fine, but the diff pair fails. I used following rule in the "Matched Net (...)
While trying to create differential pair of signals using Route flip chip signal ,I fill the advanced options form and in that I select "Named" nets under that.But when I enter the nae of the name of the nets,it says cannot find "those particular" nets in design.then **No net has been selected.Could someone help me with this?
read this document which resides in your altium help folder. AP0135 Interactive and differential pair Routing.PDF
Hello All, I have some questions about cmos comparator design. I need to design a very low power comparator. The Vdd = 3.3V, Midband Gain ~55dB, GBW ~500KHz. The current needs to be as small as possible. I plan to put the differential pair in subthreshold region and the rest of the transistors in strong inversion or (...)
Hi! I want to design the classic CMOS omp amplifier with two stages (n - channel differential pair for 1st stage and p - channel the common source stage) using theGm/IDS methodology. I want someone to tell me if the following design steps are correctly in order to obtain the DC conditions. We know that the analog (...)
Hi, I am designing a 2-stage opamp (OTA) with n-channel input differential pair. This opamp is supposed to dissipate low power( 200nW) My question is: 1) Only input differential pair transistors operate in subthreshold region and the other transistors operate in saturation region right? 2)How can input (...)
Theoretically, yes, if the input stages gets saturated by DC, then the whole mechanism collapse. In practice, comparator are not totally the same as opamp in that we often add differential type cross-coupled latch stage before digital output buffer. And even in cases where input differential pair is not really in linear region we can get (...)
Hello there, Can anyone propose good books or papers on the design of CMOS operational amplifiers? I am particularly interested in the traditional two stage CMOS approach (a differential pair and a common source with active loads). Please post any files or links