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Two Stage Cmos Opamp

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61 Threads found on edaboard.com: Two Stage Cmos Opamp
what is two stage cmos opamp. whwre is it used
We are designing a two stage cmos opamp using cadence 180 nm technology.We tried P E Allen Text book procedure but the output is getting saturated.We are not even getting the high gain.Can anybody suggest us the design which will give us around 80db gain.We need it for a comparator in SAR ADC.Please try to give the hand (...)
Hi guys, I am designing a two stage differntial opamp. I am not sure if i have to design two CMFB or just use one for both. Im not really sure what the difference is. Does anybody know?
How to designa two stage cmos chopper-stabilized OP? I want to use in bandgap.
I am new to analog design and want to practise my skills. can someone give me specs for 2stage cmos opamp design Thanks
hi guys i m final yr student and doing a 2 stage cmos opamp design. i have completed the design of the individual stages of the opamp like the current mirror, diffamp etc, i want to know how to join/interface these two stages .i.e the op amp uses the amplifiers which r (...)
Hello Can someone please explain the impact of load capacitor on the Slew Rate of a standard two stage op-amp? In addition, can the use of cascoded miller compensation improve the slewrate performance of an op-amp? I will appreciate if someone can point out the method to derive the slewrate formula for both cases. Regards
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
Hello umair9926, First of all,since you have already studied about basic concepts of cmos opamp,then the next step is to choose the circuit topology that will implement your amplifier.I suppose that the opamp you are designing is for academic/training purposes and not straightly intended for production,so starting with the design of the (...)
If you dont want to change the architecture then there are two ways of increasing gain 1)Decrease the biasing current 2)Increase the W of the input n channel diff amplifier
you can use the two stage cascode opa
how to obtain good PSRR for two stage amplifier? My stability is ok as i have put compensation cap at the 2nd stage.. thanks in advance.. a paper has explained it. <cmos op amps with improved psrr and common-mode input range>> by david b.ribner & miles a.copeland
Hi. Is anybody of you have idea how to increase the loop gain in a two-stage opamp (cmos). My circuit is the simpliest two stage opamp. Now i have 55db and i want to reach 75db at least. Thanks one way is simply increase the gm of the first stage (...)
It is up to the load and your application. Cascode OTA is a good choice, but opamp can also be designed. Just use two stage.
Don’t use a two stage approach; you will burn too much current in the second stage. Unity Gain Bandwidth = 500 MHz => for stability second pole should be around 1.5 GHz!!!!! Second Pole = gm(second stage)/(2*pi*Cload), believe me that will cost current. Normally a folded cascade should be enough to reach 75 dB, (...)
i want to design a two stage opamp with cascode compensation, just as the picture below shows. i use the capcitor Cc for compensation between node A and C, my question is, how to choose the value of Cc? for ex: resolution:10bit clock:50M swing:2V Vdd:3.3 DR:70dB PM>60deg CL=1PF then how to design this (...)
It is a quite common cmos amplifier you mentioned. You can find a design procedure in Ken Martin's 'Analog Integrated Circuit Design' book. A two stage amplifier should fulfil your purpose. Willy
yes, I agree aryajur's suggest. For 1 stage, if high gain is needed, we can use gain-boost tech. For 1 stage, there is also two structure: cascode and folded cascode.
i am doubtful whether simple two stage class-A opamp can provide 160MHz UGB.please clear me if i am wrong.i thing we have to choose the folded cascode opamp for 160MHz ugb.
hi can some one help me how to design this project? STEP BY STEP PLEASE!!! from what i should start and with wich to continiue i can not obtain all these features att all. i should use hspice 1. Obtain the features below at lowest power consumption possible at FF and SS corners of 0.35um cmos. 2. Design bias circuits 3. D
you can use folded cascode with pmos i/p pair. as it has the moderate gain and speed more than two stage. Hi,vbhupendra my plan is to use an pmos folded cascode with a source follower,the 1st pole(pole of first stage) is dominant pole,and source follower has the 2nd pole.from the settling time requi
1.hand calculate 2.two stage with miller compensarion 3.not start wit spice but calculate
In the first the capacitor makes the level shifting and the use of NMOS is better due to the higher gm for the same current than in the second case. That means the first case will be better in terms of stability with less current since this is a two stage topology. Bastos
transistor is single stage amplifier where as opamp is two stage amplifier. it can be 3 or more depend on the spec
Hi guys, I am designing a two stage differntial opamp and i need to get a swing of 0.8 V using 1.8V supply. I have to compenstate the opamp. I am not quite sure what is cascode miller compensation using a CG amplifier. Can somebody please clearify that? I have to also use CMFB. Im not sure if i can use one CMFB for the (...)
Hi, Any notes or reference for designing single supply based two stage miller all cmos books the design examples are based on dual supplies.how do i go about designing it for single supplies. thanks.
I was wondering why analog design books dont present common mode feedback circuits for single ended two-stages op-amp. Can someone propose a CMFB circuit for design of single ended differential cmos op-amp? Thanks.
Hello, yxo I think the length of the second stage depends on what you want. If you use the first stage as an error amplifier to drive a pmos like you design a LDO, it is better to use smaller size. For conventional two stage amplifer design, I think it is better to keep the length of M16,M6,M7 the same to reduce offset, (...)
The file attached is one of the best sources of information for two stage op-amps. I used it in a student project of mine. It worked vary well. Enjoy!
Hello everyone, Iam designing a 2nd order 16 bit Delta-Sigma ADC, i need to design two opamp's for two integrators. What difference should be there for both the opamp's in two integrators.Plz reply, i will be happy to reply on any clarification about the question. Regards, Srudeep Patil
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 approach (se
Hello- Here are the specs for the opamp I have: 180 nm cmos 1.8 V DC gain: 40 dB Gain at 20 kHz: about 30 dB Total current should be less than 10 nA With a two stage, miller compensated is this possible (assuming subthreshold bias at the NMOS inputs)? Any other ideas? Thanks, analogLow :roll:
Hello, I have problem with opamp transient simulation. I´ve designed several one stage structures (folded, telescopic, symetrical cmos) and all made same problem. In attachment file is simulation connection - R ratio is 1. So If I have input sinus amplitude 1 V, output amplitude is not 1 V but a little bit smaller. I don´t know, where is (...)
Hi If convenient, can you post what you have here? It's not readily understood what's meant by conventional two-stage amplifier? I thought it's better so that it's easier for those who can help you.
hi can some one help me how to design this project? STEP BY STEP PLEASE i should use hspice 1. Obtain the features below at lowest power consumption possible at FF and SS corners of 0.35um cmos. 2. Design bias circuits 3. Design proper switching CMFB for two high impedance nodes of OTA Target features of design are: Vdd=1.8 V DC gai
Normally gate and drain are high impedance node, while source is typically low impedance. But it is not always true. If the transistor is diode connected, the impedance of drain and gate will be reduced. For a two or three stage opamp, the highest impedance node is normally the output of gain stage. You could find that (...)
You can use a two-stage hysteresis comparator like that shown on page 475 of the Allen and Holberg cmos book (2ed).
I think you should give more details of your circuits . The LDO'S PSRR may be dominated by the error amplifier. In general, the two- stage opamp has poor PSRR at high frequence,because of the miller compensation capacitor. So you can try the telescope & folded cascode structure.
hello i've got a problem with comparator. it should take as little current as possible. firstly i've designed two-stage comparator with 10uA bias current for each stage. Output's voltage drives a big transistor key(W=5m L=0.5u),which discharges capacitor. Output's falling time is long, so the key isn't turned off when it should have. (...)
Please refer to the paper "A 3-V 340-mW 14-b 75-Msample/s cmos ADC with 85-dB SFDR at nyquist input, jssc,vol. 36 no. 12 Dec. 2001". A two-stage amplifer has been presented with 100-dB of open loop gain and 2-GHZ GBW by using the 0.35-um cmos process.
it's a very challenging task. 1.2v is very low and the sampling rate is too high. so i will prefer to two stage.
I'm trying to implement a 10-bit 20MS/s pipeline ADC in 0.25um cmos technology. In designing 1.5bits/stage, I have two questions: 1. In switched-capacitor sample-and-hold circuit, I use cmos transmission gate to implement switch. Usually NMOS and PMOS have same size or different size? For C=1pF, which size is better, (...)
Can anyone please provide materials regarding the calculation of the transfer function of two stage and telescopic op amps........... Thank you in advance.
if you want to reduce 1/f noise, two techniques can been thought of--chopper and auto-zeroing.
follow the following book , this is having two stage comparator design, which is useful for beginers. vlsi design techniques for analog and digital circuits by geiger
for the mentioned specs even conventional two stage opamp is suitable. Which technology u r using?. Well the design procedure is not fixed is changes according to what u want.
Can any one say why a diffrential amplifier is preffered inside an Operational Amplifier?Does it have any special advantage? Yes, it has. It has two inputs - one inverting and one non-inverting (if compared with the output phase). And that is important for a device which can be used as a universal amplifier in several fu
Is it possible to design the filter with cutoff frequency = 100 MHz and the SFDR > 70 DB with 70 MHz Input? The process is 0.35um cmos. Is it possible to implement it in active RC? In active RC, the opamp should have enough loop-gain at 100MHz to ensure the linearuity, right? If I use two stage opamp (...)
There are many, many rail-rail I/O op amps out there as commercial piece-parts. If you need both ends to be at- (or over-) rail, you may end up with two follower- buffered diff pairs (one N, one P) so that when one is cut off the other is still working. Then the trick is in how to cleanly combine the two, across the CM range. Check out all
Is is correct to use two different channel lengths in 2 stage opamp design ??? Sure, why not? I am using 0.18? cmos tech. I am using L = 0.54? in stage 1 and L = 0.18? in second stage. Will it cause offset ? Not if used in different stages. Yes, if done with (...)