phdseeker
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Dear everyone
I recently have read a biosensor paper. The author adopts a rail to rail folded cascoding structure to design a fully differential amplifier. The schematic is attached below.
My questions are
1. What is the function of the circuit as I circled in red? As far as I know, we need to provide a constant gm at the rail to rail input stage but I really have no idea why this circuit can make it.
2. Why the sizes are different in the bias circuit as I circled? I assumed that the cascoding branch should provide 2uA current so the size should be the same.
3. Why the input stage is like a differential amplifier?
Thanks in advance for all the discussions and help!
I recently have read a biosensor paper. The author adopts a rail to rail folded cascoding structure to design a fully differential amplifier. The schematic is attached below.
My questions are
1. What is the function of the circuit as I circled in red? As far as I know, we need to provide a constant gm at the rail to rail input stage but I really have no idea why this circuit can make it.
2. Why the sizes are different in the bias circuit as I circled? I assumed that the cascoding branch should provide 2uA current so the size should be the same.
3. Why the input stage is like a differential amplifier?
Thanks in advance for all the discussions and help!