questions about input referred noise power

[airboss]

Hi,

I'm trying to figure out the input referred noise power for "Sense Amplifier".

As we know that, we usually model the noise within a system as a noise source followed by a noiseless amplifer A. If the output noise power is Pop, then the input referred noise power is Pop/(A^2).

For some time segments I'm observing for the sense amplifer, the input MOSFETs are in triode region. How do I find the input referred noise power?

We know in analog design, MOSFETs are mostly driven in saturation region so we can implement amplifier. Usually, we would refer the gain as A=gm*ro.

Can I apply the same equation for FETs in triode region? I mean, can I use the gm in troide region and the Ron in triode region and then plug them into the equation A=gm*ro, and then said input referred noise power is Pop/(A^2)?

Thank you for your time and assistance.

 

[tsinghua]

You can do it. This is just an equivalent manipulation. No assumption is made to the operation of the device.