Current Mirror topology for a two stage opamp

Thread Starter

w1586569

Joined Nov 30, 2018
5
hi,
I'm currently building a two stage opamp and I'm using the basic NMOS current mirror topology(current sinking) as it was the most used topology. However, I'm not sure why I should use NMOS current mirror topology over PMOS current mirror topology(current sourcing) and it would be grateful If some can provide me some reasoning and any advantages of using the NMOS current mirror topology for a two stage opamp.
upload_2019-3-10_23-29-23.png
 

WBahn

Joined Mar 31, 2012
24,695
You might look as things such as output impedance and also supply rejection.

Also, keep in mind that the circuit you show above has TWO current mirrors in it. Perhaps the reason that one type is used in one case is influenced by why the other type is used in the other case? Something to consider.
 

eetech00

Joined Jun 8, 2013
1,660
Hi

There are both nmos and pmos mirrors in the circuit and I believe it’s to support bipolar voltages so as to limit current of either polarity..

eT
 
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