Ahmed Reda02/23/2023, 6:06 PM
Stefan Schippers02/23/2023, 6:54 PM
when this happens you must resolve the singularity. This is caused by floating nodes with no DC path fo ground. If you connect supplies and inputs of the second ota to GND the simulation will match the one of the 1st example.
Warning: singular matrix: check node net3
Tim Edwards02/23/2023, 7:10 PM
in ngspice. The value of RSHUNT can be something ridiculously high like 1E20 which wil not affect the simultion, but will satisfy ngspice's matrix solver.
Stefan Schippers02/23/2023, 7:21 PM
(Adds one PetaOhm resistor to ground to all nodes) resolves the singularity and simulation results are correct in second netlist.
Ahmed Reda02/23/2023, 7:24 PM