calibre PEX extraction problem-- immediate help needed !

[litwood]

Hello,

I'm extracting a simple circuit block (double-balanced passive mixer), which has only 4 transistors, each has 64um total width, 64 fingers. After I did Calibre PEX extraction (R+C+CC), I noticed the CC term (coupled capacitance) is extremely large, on the order of 70fF, which does not make any sense.
I'm suspecting that Calibre also extract the gate capacitance during extraction. To prove that, I did a simple test. If I reduce the total transistor width from 64um each to 32um each, but not changing any interconnect, I noticed that the CC term reduces significantly, about 18fF less.
So has any one experienced similar problem? If Calibre is extracting wire cap only, then if I reduce the transistor size, the CC should not reduce.
I'm using IBM65nm PDK. Please help. Layout attached

Thanks
---litwood

 

[akon_cn]

I only used IBM cmrf8sf(130nm) PDK, but I heard someone who used IBM 65nm PDK that It would extract the Cgs during extraction which may be a bug. I'm not sure about that, but you could verify it yourself or contact mosis if you are a mosis customer.