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Two Stage Cmos Opamp

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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 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 (...)
The loop gain is not zero. A good reference can be found from P.Gray textbook. The input-to-output connection is implicit on your opamp system (especially transistor level). The two poles are usually located at (1) at the connection between the output of 1st stage and input of 2nd stage, (2) at the output of 2nd (...)
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
I have some query! I have done simulation of two stage cmos op-amp for input offset voltage. My op-amp is PMOS input diff pair. What I did is that, I connected one input negative terminal to output. Now at second positive input terminal I applied a dc voltage of 1V. My Vdd is 3.3 V. Now from ADE I click on, I min dc op point , then went (...)
Hi, I am designing a 2 stage cmos Op Amp to meet a certain specs for my class. However, I am not sure I am understand how to set up the simulation. Attached is the simulation set up from Sedra's Microelectronics Circuits. Can any one explain briefly the setup for me, and what should I do to show: 1. Input Common Mode Rage 2. Output Swing 3. DC
I'm designing a traditional 2-stage cmos amplifier. I was getting normal looking Gain/Phase plots, but I've been slowly modifying parameters to meet requirements. However, now my Phase plot seems wierd. Anyone know the cause of this? 50925
Hi, I have Designed a 4-stage cmos opamp with +/- 0.85 Volt rail to rail supply and obtained the Bandwidth as 4.2 MHz. In order to measure the SLEW-RATE, should I have to apply a step voltage of peak values as ( V+ = 0.85 & V- = -0.85 v ). I have a confusion regarding width of Step. I think frequency of Step should be less than Unity (...)
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 (...)
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? You can read Page305 of "design of analog cmos integrated circuits" written by Razavi. this is a more effective co
All are wrong! The folded cascode is a technique to extend the common mode input range capability to one rail or a little beyond. Also the voltage driving capability for a two stage design or the output voltage range for a one stage design is extended. One stage designs are only used if you have only small cap loads. (...)
Many books say thermal noise in two-stage opamp is dominated by that in first-stage. Because that in sedond-stage is divided by first-stage gain and second-stage gain. And I did noise calcalation of two-stage opamp (...)
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
i need an opamp to use in my 2nd-order low-pass filter.the specs are: *fc=400kHz *use butterworth response what are the best specifications for an opamp to use in that lpf? i had designed a two-stage opamp but i don't know wether it is right or wrong.also,i don't know wether it is suited to use in that (...)
Hi, I would say the second choice is much better. As you know, in two-stage miller compensation, dominant pole is at the output node of the first stage (node 5) and the none-dominant pole is at the output node of the second stage (Vo). So we like to minimize the parasitic capacitance at the output node of the second (...)
you can use the two stage cascode opa
Generally, the input referred noise depends mainly on the gm of the input stage. Perhaps using a two stage amplifier allows using more of the current budget in the input pair, thus improving their gm and hence reducing the input referred noise. If you choose to have most of the current in the input pair and a small fraction in the output (...)
hello do you now how to increase simple two stage opamp's SLEW RATE without significant increasing bias current of the ouput stage? if you had any schematics, please post it regards
In conventional two stage opamp the miller cap is added between first dtage and second stage. This is frequency compensation and helps in making one pole as dominant pole and pushing the other pole towards infinity. For the second pole ater compensation the RC product is approximately going to be same so,
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
who can tell me why the simulation result is that as follows? It's closed loop opamp,with the ratio of cap being 2:1.I used two common mode feedback,cuz the opamp is two-stage.I use Ahjua compensation.The schemetic is as follows. The simulation is run several periods to make CM voltage stable .But the (...)
a two-stage opamp,first differential ,second cascode,my question is my gain is 94db,but pm<0 ,about -40, and CL=1p,both stage is single ended output. to my surprise, when i use a small compensation cap(<1pf),it doesn't work;however, when i use a big compensation cap(>10pf), the pm improve a bit,but the gain of (...)
I want design a two stages fully diff-opamp. But in many textbooks,each stage needs a cmfb circuit for balancing. maybe there are some two stage fully diff-opamp just using only one cmfb~!! who has any information about it ? thanks in advance~ Yes, u can (...)
Hi, This is an two-stage opamp with miller compasation cap and Vdd=1.8v, Vss=0v. I am measureing the input referred offset voltage (Vos) for this op-amp. I bias DC=0.9v for both Vin+ and Vin- and AC=1 for the Vin+. Then, when Vin=0.9v, the Vout=0.912v, where both vout and vin are in the transition region(linear region) as shown in the (...)
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.
I am going to design a CMFB in two stage folded cascode differential opamp. according to the , somebody said "we need to have two cmfb circuit in two stage." is it correct that two cmfb circuit is needed in two stage folded cascode (...)
Yes negative PSRR is a little more tricky. The best reference potential for most analog simulation is a chip external ground. The internal ground is the substrate. Nearly all components have a connection to substrate so it is the net with the biggest fanout. I ahve foulnd this gives also faster full chip simulation with full packgae parasitics if t
Can anyone tell me what's the typical noise value of a two-stage opamp at 200 Hz?
Hello, everyboody! I doubt my design procedures of a two-stage opamp, so I described these procedures in below and invites everybody point out the mistakes. thanks! If the specification of the opamp (like DC gain, Unit-gain bandwidth(Wu), phase margine and slew rate) is chosen: step1: Design the transistor sizes (...)
My opamp is used in pipeline ADC as MDAC opamp. I use two-stage structure, the first stage is telescopic with the output common-source stage. My query is that whether the ouput swing of the first-stage should be large or not.. when the opamp is in the (...)
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, (...)
Hi all, I am designing a two stage folded cascode opamp. Specification of load capacitor has very high range. The minimum load cap is 470pF and maximum is 100nF. I am finding it difficult to compensate this opamp. With 470pF load capacitor, the output node becomes second pole and a miller cap will help to compensate (...)
i want to design a two-stage opamp with cascode compensation ,and the first stage is folded cascode structure, the requirements as follows: resolution:11 bit clock speed: 20M CL=2pF,Cs=Cf=1pF,DR=70dB,Vdd=3.3V,output swing= +/-1V then how to design the two-stage opamp (...)
i have designed a two stage opamp with cascode compensation, the following is the circuit diagram, and the design specs are as follows: clock rate:12MHz CL:500fF ~ 4pF Av>90dB CMIN:0~2.2V (Vth0 = 0.7V) output swing:0.1~2.2V power consumption:as small as possible in my design, the power supply vdd is 3.3V (+-10%), Ca=Cb=800fF, (...)
Hi, I am running a pole zero analysis via cadence spectre on a two stage opamp which consists of the classical diff pair with current mirror load and as second stage the classical common source/inverter problem is that i cannot see the RHP zero that is created via the feedforward path of the miller compensation (...)
in two stage opamp, such as telescopic + common source (as the figure shows), or folded cascode + common source, with cascode or improved cascode compensation, how to improve the PM of the opamp? first, how to decide the bias voltage for the opamp? assuming that the operating frequency is 20M, and CL=5pF, (...)
I would suggest you look into cmos analog design book by phillip allen ( 2nd edition). it has a chapter which discusses how to design two stage amplifier and the trade offs. do not test your amplifier in open loop, have a closed loop system which a big resistor(1GOhms) between ur output and negative input. this will help u calculate (...)
I assume you mean 60 degrees for PM, not 60dB. For the specs you've given, a standard two-stage Miller compensated op amp will do. You can look at the following references:
Hallo, professor asked me about the offset voltage in a two stage opamp.All the M are same , M1 and M2 have the same gate voltage . but why does VA not equal to VF???? please help me . 68926
i am designing two stage miller compensated opamp which has differential inputs vinp and vinn and single output vout.the first stage is simple differential amplifier and second stage is common source which is compensated by miller capacitor and an NMOS(in triode region) . My question is: How can i sweep (...)
Hi everyone, as seen from the title, i need your help in finding an example in how to design a PMOS input two stage opamp. The type that will guide us in transistor sizing. I've not been successful in finding.The examples in NMOS input is plenty though. Please help. Thank you!!
94899 Dear all, I now design a two stage opamp,as the first photo, the tran simulation of the first stage output the differential input and second stage output are shown in the second photo, why the second stage tran simulation results is like this one? I thinl it's wrong, but i don't know (...)
I was asked this question during a interview, they asked me to draw a cmos single end two stage op amp, and then told me for all transistors Vdsat=0.1V and Vth=0.3V, besides, the inerviewer also provide Vdd=1.8V and Vout=0.9V, I was asked to tell the DC operating point from node 1 to node 5, can anybody teach me how to solve this? Please (...)
Hi all: I upload two type two-stage opamp: NMOS input and PMOS input. Because a PMOS source follower will clamp the power supply value when the source is connect power supply directly. So I have a question: Why A Classic the output stage of nmos input two-stage (...)