AC analysis for differential amplifier in cadence

[sastry]

cadence ac analysis

hi

i am trying to run ac analysis for differential input differential ouput amplifier in cadence.what is the setup for it
i have given ac magnitudes as 1 and offset voltages as 0.
the inputs are at phase difference of 180
and i am sweeping it for a frequency range.
is there anything else i should take care of

regards


sastry

 

[Usman Hai]

ac analysis of differential amplifier

It seems fine. Just make sure that you are also providing the common mode input to the opamp as well.

 

[sastry]

analysis of differential amplifier

what is common mode input for differential amplifier

 

[edge_tv]

ac analysis of an amplifier

Common Mode is the Bias Voltage for the Input Transistors of th OP. You can use an Ideal_balun from the cadance Lib (analogLib) .You can set the commen mode and the diff. signal seperatly, (put into you simulation, port left up is the diff. signal and and port left down is the CM, on the right side you find the tow ports which goes to your amp). You can use the Balun also for the output, to seperat Diff signal and CM