Output resistance of single transistor

[taofeng]

Hi ,

I am wondering how to increase the output resistance of single transistor even in different load conditions.
Thanks !

 

[srieda]

r0 ≡ Va/Id => r0 is proportional to L/Id

thus r0 can be increased by increasing the length of the transistor or by decreasing the current... logically this means that the channel length modulation factor is less and you'll have a near ideal current source behavior from the transistor...

hope this helps!

 

[gevy]

You can use self-cascode to increase output resistance of transistor.
It is better than increase L.

 

[srieda]

how to do self-cascode of a 'single' transistor?

 

[taofeng]

but the gm will become small, that is a bit annoying .

 

[DZC]

What about regulated cascoding
How do U conclude the gm's gonna reduced?

 

[rania_hassan]

I think that regulated cascoding (as DZC said before) (unknown also by Gain Boosting technique ) will provide you will high output impedance with the same headroom consumed by single transistor but with more power consumption.
best regards,
Rania

 

[meseasky]

what is the self cascode? how?