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# Fully Differential Mode Output

36 Threads found on edaboard.com: Fully Differential Mode Output

## adjusting output common mode voltage

I am trying to design the fully differential opamp. I put all the values according to mathematical calculation and put those values in simulator. After some simulation, some transistors are going to linear again against the calculations. I found a very high value of common mode voltage at output node. I tried all the means (...)

## [Moved]: fully differential OTA with CMFB

Hello Can anyone help me in designing a common mode feedback circuit (CMFB). I have applied a 100mV DC common mode input voltage at the input of a differential pair with no Ac signal. My fully differential amplifier output common mode DC voltage is 456mV at one end and (...)

## On Settling of a fully-differential amplifier

... However, if we look at the differential signal (Voutp-Voutn), the influence of the CMFB vanishes. The differential signal seems perfect. Comparing the single-end signals and the differential representation, we may conclude that the former are not well settled, whilst the latter is well settled. (Confusion??)

## Switched capacitor output common mode

I am designing switched capacitor biquad low pass filter. I have some questions regarding the design. About my design : 1. Cutoff frequency = 1KHz 2. 65nm LP process 3. Clock frequency is 50K There are 2 integrator in my circuit. It is a second order filter. It is not fully differential. My question is How am I supposed to set dc out

## Fully differential op-amp model on candence

Dont connect the bottom node to ground, instead bring it out as Vout-, name Vo as Vout+. This should give you a fully differential design. Break the Ro and connect its middle point to a voltage source (VoutCM) to define the output common mode voltage.

## How can settling time of fully differential amplifier be computed???

I am able to find the settling time of single ended opamp by placing it in unity gain configuration mode. but now if I want to find the settling time for fully differential opamp then can it be simulated using cadence tool. If any one knows it then please suggest me the steps that will be helpful. Also you can mention the links.

## A Simple OTA Question

This is a simple two stage OTA ... with fully differential output at first stage and single ended at the second stage. Gain will be approx gm^2 (ro || ro)^2 .. assuming the all the ro and gms are same. The MOS arm connected to VB2 is used for CMFB (Common mode Feedback) as the first stage is fully (...)

## Common mode feedback circuit

Hi, Can common mode feedback circuit correct the offset of a fully differential amplfier?? Till now, i thought it will correct the offset voltage, But when i am doing the simulations its not correcting the offset, its just setting the output common mode voltage. please help............. (...)

## 2stage DM folded cascode's 2nd stage??

so for following specs, I am trying to use folded cascode followed by common source amp. i did the fully differential mode folded cascode n got around 76dB gain with all other specs in line, my question is how to add CS Amp at out of folded cascode? 1. 2 CS for each output of DM Folded cascode? 2. any voltage level (...)

## CMFB and Operating Floating Amp

fully differential opAmps always need a CMFB. Here, the CMFB stage is already integrated: M41 - M46 . The common mode feedback works from M46 into M36 , whereas M43 to M34 as well as M44 to M33 provide positive 1/N feedback to the output stage.

## common mode problem in sc-ampliier

dear all, now i found a problem in design fully-differential sc amplifier used in pipeline adc: my supply voltage is 1.2V, and all of the common-mode output of op are 0.6V to max the swing. however, from the schematic we can know that the input common-mode voltage is been setted at 0.6V, but the input (...)

## Differential OTA - Transient Output Swing Question

I am simulating a fully differential OTA for a class project. I have the basic specs where I would like them (like gain,BW,PM). But, when I run my transient sims, I am seeing Vout and Voutb are not symmetric. Both are pulled up to about the common mode votlage of 1.1V and then are clipped. My differential (...)

## fully differential switched capacitor amplifier

hi, Can anyone please clarify- 1. I have read somewhere that while in the holding mode, the input common mode voltage of the differential amplifier is equals to output common mode. Does that necessitates the vcmin range should include vcmout? If not what will happen? 2. what should be the input voltage (...)

## A question about input bias for a fully differential amplifier

I have a question about the input bias for a fully differential amplifier. As showed in attached file. 52186 There I have a single-ended input signal at the port Vin+, how can I creat the DC bias for another input Vin- from the positive output? Thank you!

## systematic dc offset voltage in fully balanced opamps

I expect any decent fully differential amplifier, will have a common-mode reference and common-mode feedback circuit. Your dc offset voltage is still the input difference at output null (difference). I prefer to use controlled sources with a ground referred output to pick off the (...)

## common mode feedback malfunction?

Hi, I have designed a fully differential opamp.It's a folded cascode archtecture with gain boosters.Each module has it's own cmfb circuit.After adding the cmfb and after substistuting all ideal things of the schematic (dc voltages sources) with the respective biases from the biasing circuitry,i notice that my output node's common (...)

## MDAC problems in the pipelined ADC

If your opamp is fully differential, do you have CMFB circuit for the output common mode? If yes, and if it's reference is different than 0.5v, check what happens with it and why it is not able to control the output common mode. Attaching a circuit will be helpful.

## how to simulate slew rate of a fully differential op amp

I have designed a fully differential op amp. I do not know exactly how to measure the slew rate for a fully differential op amp. Generally for a single ended op amp we connect the op amp in non inverting(feed back) mode and measure the slew rate. How to measure the slew rate in case of (...)

## CM voltage in a fully differential SC cmos integrator

in designing an fully differential integrator for a second order sigma delta modulator. how to choose the input and output common mode level voltages for the OTA used as integrator. Help me please, its urgent. Thanks in advance.