celebrevida
Member level 2

In the project I am working on there are various 1 or 2 stage opamps.
(a) Simple Opamp (b) Current Mirror Opamp
I am seeing the following two types of first stage topologies.
But it isn't clear why (b) was chosen instead of (a) in certain sub-cells. I literally swapped out (b) with (a) and it seems to work just fine.
If we assume that there is a B:1 ratio in output current vs Itail in (b), then my understanding is that the current mirror opamp has a factor of "B" increase in Gm, GBW and SR but the same Av.
I guess it isn't clear why the previous designer chose (b) over (a) in those cases. If (a) is "good enough", why consume more area and power? Why am I not seeing?
Thanks in advance for any insight.
(a) Simple Opamp (b) Current Mirror Opamp
I am seeing the following two types of first stage topologies.
But it isn't clear why (b) was chosen instead of (a) in certain sub-cells. I literally swapped out (b) with (a) and it seems to work just fine.
If we assume that there is a B:1 ratio in output current vs Itail in (b), then my understanding is that the current mirror opamp has a factor of "B" increase in Gm, GBW and SR but the same Av.
I guess it isn't clear why the previous designer chose (b) over (a) in those cases. If (a) is "good enough", why consume more area and power? Why am I not seeing?
Thanks in advance for any insight.