how to choose which transistor to use in TSMC 0.18

[ccw27]

Hi,

How do I go about choosing which transistor type (i.e. nmos2v, nmos2V_dnw, nmosmvt2V, etc) to use for a particular circuit? Is there a particular rule?

Thanks

 

[qutang]

i think there must have some readme to describe the transistor.

 

[ccw27]

Basically what is the difference between nominal, medium, native and rf device from a circuit designer point of view.

thanks

 

[lokeyh]

I think it depends on the threshold voltage of the transistors you want.

 

[borodenkov]

There should be 2 pdf documents in your PDK - one about SPICE simulation of devices for high frequencies (RF) and another one - for lower frequencies. They contain all info that you need.

In brief:

nominal device - transisitor with normal threshhold (smth around 0.4 V as far as I remember, it also slightly depends on the size of the transistor)

medium - low Vt transistor

native - zero Vt transistor

These 3 models of devices are for low freq. For igh freq there's just one type of transistor - rf (although its model is more complex)

 

[uladz55]

to borodenkov

Do these Nominal, Native, Medium model transistors have differense in Layout?
How to distinguish these transistors?

 

[borodenkov]

yes they differ (simply because in the layout you need to show to fab which kind of transisitor you want to use)

 

[Question]

you can get the help file from your PDK.