TSMC 0.18um Spice Model

[emeraude]

Hi!..Im a newbie in analog design. Right now im designing an opamp in 0.18um technology to be used in a microcontroller operating in 26MHz. Which model should i use in my simulation? Because in TSMC 0.18um spice model they have RF model and baseband model. Which should I use between the two? Your expert opinion will e very much appreciated. Thanks in advance.

 

[jjx]

First: are there two different models or two different transistors? Could it be that the layout of those two looks slightly different?
Second: Do you refer to the comparison between the TSMC RF and TSMC GP/LP nodes?

If none of the above - the RF model is generally more accurate wrt. parasitics, such as the gate resistance or other "small" parasitics that could be influential at high frequencies, but that can be neglected at "lower" frequencies. For 26 MHz I would probably go for the simpler model, i.e., no use for the RF model. On the other hand if you are "only" designing the opamp (say 20 transistors) it wouldn't be much of an overhead to use the RF model.

If yes to either of the first two question it could be a more complex answer

 

[emeraude]

Meaning it is also safe to use Baseband model (TT, SS, FF, SF, FS) for 26MHz application... If so, then I might not anymore consider RF model in my design. Though its more accurate in terms of parasitic and noise considerations, however it is more complicated to use, its because i have not used it before. Also because i will also perform StarRC, parasitic extraction tool of Synosys, after layout to address parasitics.

 

[jjx]

Yes it should be. Some more info on RF MOS (related to my two first questions above) in this thread: https://www.edaboard.com/threads/214567/