CMRR AND PSRR for a fully differential amplifier.

[suchendranath]

psrr of instrumentation amplifier

hi,
i am trying to simulate CMRR and PSRR in cadence spectre.
my specifications are.. 2 stage fully differential switched capacitor comparator.
kindly help me in simulating CMRR and PSRR for a fully differential amplifier in CADENCE SPECTRE..

 

[DenisMark]

psrr in differential amplifier

Here is example

But in this paper CMRR and PSRR are simulated by incorrect way. Generally CMRR and PSRR are related with input offset voltage. So the worst case CMRR and PSRR value can be obtained though Monte Carlo simulation.

 

[siddharthshukla]

fully differential amplifier

there is a fundamental flaw in your question. A fully differential opamp has a PSRR of infinity as the power supply variations are cancelled when we take the output differentially.

 

[DenisMark]

comparator psrr

Don't care about siddharthshukla message. There aren't ideal circuit in real world. Independently of how we take output (differential or single).

 

[milkdragon]

fully differential amplifiers

for PSRR, put an ac source (Vmag=1) at your supply line. for CMRR, tied the differential input together and put an ac source (again, Vmag=1)

For both cases, use AC analysis, sweep frequency, and look at the output.

You will see the frequency response of PSRR and CMRR. In practice, you should see PSRR and CMRR degrades at high frequency