need help with RF circuit post-simulation problem

EDAboard.com Forum Index -> Analog IC Design & Layout -> need help with RF circuit post-simulation problem

Author

Message

happyree

Joined: 24 Apr 2009
Posts: 6

03 Jun 2009 4:17 need help with RF circuit post-simulation problem

Hello everyone!

when I do post-simulation with assura extracted-view after the lvs and rcx step, I find an odd problem.

As is showed in the picture a rf_mim cap is directly connected to the gate of a MOS transistor. But their DC voltage are different. And it seems the rf signal of the two points have no relationship. Besides, I found that DC voltage of all the "plus" of other rf caps are 0 V.

before, the post-simulation results were right. Then I did some changes and copys of the shematic and layout, this problem comes up. If I delete part of the circuit and layout , it disappears. but then I have to redraw the layout, it's too much work.

so I hope someone can help about this.
Thanks a lot!