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Design review: Fully differential telescopic Operational amplifier.

Alex_bam

New Member
Hello,
I used Behzad Razavi's book to design a fully differential telescopic op-amp [screenshot attached]. Then I follow the same steps to design my proposed opamp, but I am not getting the desired result. Can someone point out where I'm doing mistakes?
For your reference, I have attached hand calculation and simulation screenshots. Thanks
My design specifications are: Supply voltage: Vdd=5V, Output voltage swing: 5V, Power ≤ 5mW, Gain: 500, UnCox= 151uA/V2, UpCox: 26uA/V2, Vthn=0.84V, Vthp: |1V| .
 

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rjenkinsgb

Well-Known Member
Most Helpful Member
I'm not familiar with that design, but from a quick look, VB1 and VB2 should come from voltage dividers or references??
As it is, the gate voltages look like they will be the same as those of the current source gates etc.

See the last paragraph of the text page you include; "The minimum value of VB1 ..."
 

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