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What is the gain of a NMOS diff amp with PMOS loads?

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suhas_shiv

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Re: Gain of Diff Amp

What is the gain of a NMOS diff amp with diode connected PMOS loads (like an OTA) and a PMOS diff amp with NMOS doide connected loads? I calculated the gain as gm(nmos)/gm(PMOS diode connected) for first case and

gm(PMOS)/gm(NMOS diode connected) for the second case.

Also I am attaching a comparator figure. How would you go about designing it ?
The input is about 0.2V to 0.4V differential, 600Mhz pulse(or random data). The current required at the output is about 1mA(hence Iss=2*Id=2mA) for the load of about 150-200fF( risetime at output is appr. 400ps). The expected output waveform is a 0 - 1.2V 600MHz pulse(or the random data) signal.

What kind of biasing would be good for 2mA? Current mirrors are efficient only for around 100uA or so.

I would appreciate any inputs on this. Thanks.

Added after 5 minutes:

oops can't see the attachment. So I will try to attach it again.
 

suhas_shiv

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Re: Gain of Diff Amp

oops can't see the attachment. So I will try to attach it again.
 

suhas_shiv

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Re: Gain of Diff Amp

Anyone with any inputs??
 

liccAMS

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Re: Gain of Diff Amp

Is there a wrong connection in your circuits?
the left PMOS.
 

suhas_shiv

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Re: Gain of Diff Amp

Yeah, the gate and drain should be shorted instead of gate and source. I have already corrected that. Any ideas on how to go about the design intially?

Thanks
 

wwwzhenghao

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Re: Gain of Diff Amp

i can not see your schmatic,why?maybe you can read allen's book about op.
 

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