We have an ADC in TSMC 65n
Simulation with schematic is fine - works great.
Simulation with extracted C (QRC) is fine - works great.
Simulation with extracted R (QRC) - oh dear.....performance is terrible.
Fair enough - could be crap layout - so I set all the extracted resistors to 0.001 ohm - I would expect it to perform the same as a schematic simulation - performance is still terrible ?
The ADC is switched capacitor - checked operating points of relevent blocks - all in "right" place.
It looks like spectre is removing various instances during topology check, so i used 'preserve_inst' to stop this. Performance is still terrible.
The schematic (due to size) was run with 'liberal' as was the R extracted view. Changing to 'conservative' makes no difference.
I even run spectre in 'non aps' mode. Same terrible result....
I have looked at the ERC results....no soft-connects...
Going quietly mad here.....