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.....
Comparing waveforms of one of your working simulations with those of your "terrible" one for important nodes in your circuit might help you identify the place where the problem occurs and guide your search for the cause.