Hi :
I have being modeling a 2nd DT sdm using verilog-A. I have model the diff-ota with verilog-A, and I use ideal switch in analogLib.
the diff-ota verilog-A model ac and tran simulation result is right.
but when I put these model in sdm , the simulator accuracy setting is conservative , when simulation the simulator will have convergence error, and I could't get the result.
when I change the simulator accuracy setting to moderate, the simulator will have no error, and I will get the result. but the result has more harmonics.
Is my diff-ota modeling has problem , or  modeling the switch cap filter has some special requirement to the ota verilog a modeling?

Min

Do you need to model the switch as a separate entity? I have had great success combining the amplifiers and switches into one behavioral model.

-Ken