hspice gm is frequency independent ?

[mike_bihan]

Hi, all:

Did hspice included the variation of gm (CMOS) over broad frequency upto 20G ?

Since it takes electrons finite time to pass through the channel, so there will be a up-limit frequency above which eletron will forever stay in the channel.

Did hspice take that into account? In another way, if no parasitic capacitance exists, will the cut-off frequency of mosfet in hspice simulation be infinite ?

(The reason I did not do the test it myself is that it looks that impossible to remove all cap in the process file, maybe some avanti guies can answer this problem. Anyway, gmo is frequency independent)

 

[superluminal]

-You did not mention the level you want to work with , because every level has its set of equations for Id & gm.

-Depending on the level you work with, you can set the parasitic capacitance to zero by setting, for example, AS/D & PS/D to zero. However, this will also depend on your capacitor model option statement & the capacitance model used in the model ( level ) you choose.

-The best that can show that is the " True-Hspice Device Models
Reference Manual" . you will find it on your directory. Actually it very good to read & it will answer all your questions.

I hope this will help you.