I have a circuit comprising one OP-77/AD op-amp that is basically a Sallen-Key filter with some other resistors and capacitors around it. All capacitors use a tolerance (10%) and all resistors use both a tolerance (1%) and a tempco (100 ppm/C).
I've had convergence problems during worst-case simulations at some temperatures. The OP-77/AD seems to be at the heart of the problem but I'm stuck with it because I'm analyzing an existing circuit.
All of the power supplies (+/-15V for the op-amp, and +5 for another item) have both 5% voltage tolerances and 200 mVpp noise at 20 kHz bandwidth.
I've made these modifications to the default simulation settings: VNTOL = 1E-4 ABSTOL = 1E-10 GMIN = 1E-9 ITL1 = 5000 ITL2 = 2000 ITL4 = 2000
Is there something else I should do to enhance convergence?
What about the solver? Is the default best? What are solver 0 and solver 1?
Is selecting GMIN stepping helpful?
Thanks,
Bob Penoyer