130nm to 65nm design question

[mischivis]

If I take an opamp design from 130nm to 65nm but keep the same W/L's for
everthing, will my open loop gain increase or decrease? I guess what
I am asking is for a simple op amp stage where the open loop gain is
gm*ro (for the sake of arguement), what will happen to gm and ro going
from 130nm to 65nm if I keep the W/L's the same?

 

[chris.mourad]

Hello

Difficult question to answer. It is not that straight-forward.
What I know from my experience:
Going down through technology nodes has several advantages, such as less parasitic capacitance, better gm performances, better output impedances... Tendency is that performances of the circuits are better.
I am afraid you cannot draw a clear conclusion. The key is simulation.
You need to resimulate all the circuits you are transferring to 65nm node. By then you will be able to tell what has changed.

Cheers
Christian

 

[edwinc]

Change technology allows to improve circuit performance, but when technology parameters are changed a circuit should be recalculated. In my experience I have to adjust sizing for some circuit designs when I change technology. In the other hand, if operating point is different at the new circuit, its performance could be better or worse. Thus is not easy to determine the new performance. You should simulate new circuit and verify its operation.

 

[leo_o2]

In fact, it depends on technology. Why not to have a simulation?

 

[gift4jo]

Avoiding redesign the circuit and also minimize the layout change, (in other word only circuit tweaking), personally I prefer to tweak the size of the current bias transisitor.

It might be useful if you can generate two sets of gmId lookup charts for both technologies so that you can have rough idea how much the transistor perfomance is changed.