Hi,there!
I have designed a pre-amp and what to know the ICMR and noise of it.I use spectre to do simulation.
But how to find the DC gain with common-mode level Vcm changing?
The circuit is a diff. pair with diode corrected transistors as load,and output is also diff.
I made dc sweep with variable Vcm,and plot the expression
deriv(Vout+) to see the output,is the result is DC gain with Vcm changing?

Furthemore,when I run noise analysis,I find that I can select pos.&neg output as output noise,but the input noise,but the input voltage source can only select one,and my diff.input is fed by two voltage,then what should I do?

Thanks a lot!

urian