Thanks.
Quote: The transit frequency is fixed by the process.
With "process" did you mean "technology"? To be honest, I don't know the difference between "process" and "technology".
If so, in my design, I use TSMC 130nm then "transit frequency" will be fixed, right?
According to the definition above, transit frequency = gm/Cgs. And therefore, it will depend on gm and Cgs. In other words, it will depend on the biasing condition.
Why can we say that it only depends on process?
Quote:But bear in mind that if you were to add additional capacitors here and there (for example across Cgs), you could reduce the effective transit frequency and thereby lower the gain.
Yes, I see that from the formula transit frequency = gm/Cgs and the product of gain and bandwidth.
Quote:Also, don't take the authors words to mean that the design is linear, as gm/Cgs is a nonlinear function of the biasing condition. I think the important point is that your Gm is optimized alongside your fT.
Yes, however, I still confused why the author said so. It is clearly that Gm depends on bias conditions.