number of fingers ads nmos

Hi,
Has anyone ever used TSMC 0.18 design kit? I met a problem now. I don't know how to set the width of channel for NMOS device. The default value of wr=2.5 um and can not be changed. Is the channel width ralated to nr(number of fingers)? If so, what is the relationship between channel width and number of fingers? Thanks a lot.

if this is the RF transisrtor , it cinsistis of multiple channels in parallel , so if u want to change chare the N factor , as the multiplies of the 2.5 um

khouly

Thanks Khouly. One more question:). I computed the channel width as 2.5*nr. However, in my Gillbert mixer DC simulation experiment, I found the bias current of simulation result was half of calculation. It is quite strange. Have you ever met such problem? Thanks.

no i didn't face such problem , but take care if ur using the minimum length transistor in ur circuit this transistor current will be different coz the channel length modulation u neglected in ur calculations

and if u want just upload ur project , and i will try to check it

khouly