I am designing two stage operational amplifier in CMOS technology. After sizing all transistors and preeliminary checks I wanted to determine input offset voltage of my circuit, and browsing many pages with simillar questions, I actually did not find answer that would make thing clear for me.
First of all, most of the answers in that topic assume that by applying only common voltage to both inputs the Op-Amp output would be 0, which is basically not truth, as there will always be some Common Output Voltage. And this Common Output Voltage is already affected by Input Offset Voltage.
And here is where I am unable to handle this problem. I think applying any resistor divider etc could not work as any obtained result will be useless without knowledge about common output voltage. That seems as a vicious circle to me.
Should I just make spice .op to make input pair's VGS to be equal, or there's a better way to simulate the offset value?