Dear Sandeep Kumar ,

In the schematic level all transistors have the same symbol no matter their threshold voltage is. You can differentiate between the transistor by assigning different names to them. Then the .model is different for the two transistors where they have different threshold voltages and also other model model parameters such as cox.

If you want to differentiate them on the schematic level then you can make a new schematic symbol of the high threshold transistor.

Best wishes

Sir, in scematic to spice netlist, after including model card all the NMOS and PMOS transistors are modelled according to parameter description of model file. So how we can get specific transistor with high threshold voltage? Is it possible to add another model card for specific transistor?

Yes, by assigning different name to transistor and modifying the same name in model card now i am able to add another model card for specific transistor.

Dear Sandeep Kumar ,

I don't know what type of circuit your are designing, but I suggest you to use transistor model parameters of an available multi-threshold CMOS (MTCMOS) process, which provides both low- and high-threshold MOS transistors.

In this way, you can also be sure that your results are more realistic (i.e. based on a real CMOS process).

As I said, I don't know exactly what your application is, or whether you need transistors with special properties, but, in any case, I hope you find my suggestion helpful.

Best regards...

Dear Sandeep Kumar ,

I would suggest few points for MOSFET transistors, hope this will help.

1. You can use a material with high permittivity in the fabrication of transistor (conventional approach).

2. Keep doping of source and drain very high compared to the doping of the channel (practical approach).