4 GHz clock generator design --> RF MOSFET vs Standard mosfet

[GRLEE]

Hi.
I am currently designing a 4GHz clock generator using tsmc 65nm RF technology.
In general, "RF" bring to mind fast speeds.
However, The transition speed is faster when using a STANDARD MOSFET than when using an RF MOSFET.
If anyone knows the reason, I would appreciate it if you could reply.
Thanks.

 

[dick_freebird]

RF models strive for accuracy in frequency responses, losses, gain etc. Digital models just need to match characterized timing and how, is a lesser concern.

RF models will include parasitics the plain ones don't. Extraction rules should prevent "double counting". But try and be clever and you might succeed at fooling yourself. Bet that support and advice will be more forthcoming if you stick to the script.