What are the effects of process variation on gain?

[estradasphere]

what are the effects of process variation on gain? do we expect a larger gain at "fast" than "slow" and why?

thanks

 

[evilguy]

Re: process variation

as i know the drain current for fast process is lower than typical. Idfast<Idtypical<Idslow. depend on the circuit. if the circuit gain is linearly dependend for drain current we can aspect that gain will reduce as drain current reduced.

 

[mark_nctu]

process variation

Mybe your bias circuit is sensitive to process variation.

 

[bbbb]

Re: process variation

I think a few dB variations of gain in different process corners is normal. if higher, there is something wrong with the circuit.As long as I know there is no general rule:e.g. the FF corner may have larger DC gain than SS because of larger uCox and thus larger gm. On the other hand, Vds of some transistors may be reduced in FF which in turn results in lower ro.

 

[sapphire]

Re: process variation

The gain should be independent of process variation, ideally.

 

[raduga_in]

Re: process variation

Fast transistor means it has low VT, thin oxide hence
we can expect the Beta of the transistor which is a
process dependent parameter to increase form its typical value.
Hence you can expect a little increment in the gain as this increased
Beta will increase the Gm of the transistor.

Added after 8 minutes:

Here you can find a bit of about the exact equations
related to process variation.