#### suhas_shiv

##### Full Member level 2

**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.