Dear friends,

I have designed the same circuit shown below, . the circuit use two common mode feedback circuits, the first one that adjust the common mode voltage between o1p and o1m while the second one is not shown but it is contrroling the output voltages vo1 and vo2.

I have no issue of the outer common mode voltage as the common mode voltage is simple I set to VDD/2.

For the internal one I have simulated the circuit to know the common mode voltage between vo1m and vop, this voltage I provide it by meaning of ideal voltage source, seems every thing is fine. Now I want to represent this voltage by real design.

one easy and direct solution is to provide it by stacks of dioides connected to a current source, by adjusting their ratios I can reach the value I want. However, this voltage is static and it is not sensitive to common mode voltage of the inputs when it is changing.

Therefore, I would like to ask your help to suggest me with such biasing voltage, I roughly read that I need to make a replica circuit of the input stage, how it looks like ? below is my try, is it correct ?

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Thank you a lot