Transistor transconductance

[sykab]

Can anyone tell me why transistor transcondutances are the most important paramenters in opamps that must be stabilized?

 

[jecyhale]

Can anyone tell me why transistor transcondutances are the most important paramenters in opamps that must be stabilized?

I think transconductance (GM) is the core of OPAMP.

If it can't be stable, how to confirm the stablity of OPAMP?

 

[lladnar23]

In an opamp, there are a few important specs. First there is the gain, which is expressed in terms of gm*R terms (for each stage). So you see that when gm changes, the total gain changes. However, this isn't usually a big deal, since the gain is made very large, and small variations don't matter much.
The bigger reason that gm is important is that the frequencies of the dominant pole and the non-dominant pole depend on gm. If these frequencies change, the bandwidth of the opamp changes.
So you can see that gm has a big impact on the gain and bandwidth of an opamp.