how to simulate fully differential OTA for transient and step response...please help

[raditsme]

hello all,

i have designed fully differential folded cascode amplifier. i have done its AC simulation (AC response, gain, phase UGB etc.) only.
but don't know how arrange the setup for transient and step response. i want see the settling time etc.

I know how to do it for single ended amplifier...where we have to make unity gain configuration etc. but don't know for Fully Differential Amplifier..?????

Please provide me figure of the setup to do it. I am driving capacitive load and this opamp is to be used in sample and hold application.

Please help.....

 

[lebevti]

by transient response I'm assuming you mean impulse response?? - use a square wave signal as input (VPULSE), and set the pulse width to be extremely low compared to your period, so as to simulate a delta spike.

step response - also use VPULSE input, and set the period to be long and the pulse width to be almost as long (say, 99% of the period), so that it simulates a unit step funtion

your outputs in each case will be periodic, but within one period of your output you will be able to see your step response and impulse response

in each case, use the Transient setup

 

[crutschow]

For a differential amplifier you want to test each input individually, just as for a single ended amp, with the other input grounded.

You may also want to check the common-mode rejection by applying the same signal to both inputs simultaneously and seeing how well it suppresses the signal.