I am designing an Instrumentation amplifier using differential difference amplifier. I want to calculate CMRR and PSRR.
Please help me how to plot them using cadence virtuoso.
You could use the xf analysis in spectre. You'd have three sources at the input - one representing the common mode signal, one representing the differential signal (so that could be between the two inputs, with the other source providing the offset), and then the source supply.
With the xf analysis, you'd specify the frequency sweep and the output of the circuit. Then after simulation, you could use the direct plot form and find the transfer function from each of the three sources to the output from your single simulation run.