OPA192 Simulation Bug?

ErnestHanks_55

Other Parts Discussed in Thread: OPA192

Hello TI,

There appears to be an error with the OPA192 AC analysis.. the AC analysis seems to create a mysterious error at low-frequencies of an additional ~-11 dB?

When operating in transient simulation, there is no loss at these lower frequencies and model operates as expected without the mysterious attenuation...

And if I use a different op-amp it works fine (so its definitely the OP192 model and not my simulation).

TI can you explain?

*Note: Circuit1 has an additional -6dB (1/2 voltage gain) from 50-Ohm matching

*Picture2 transient is working as expected; the buffer shows a circuit gain of -1/2, whereas the inverter has a gain of -1.

over 7 years ago

0 Ian Williams over 7 years ago

TI__Mastermind 27715 points

Hello Ernest,

Thank you for bringing this issue to my attention. There is a problem in the netlist where all capacitors had initial conditions of 0V, seen as "IC = 0" at the end of the line where they are instantiated. This was causing no problems in TINA, but had strange effects on DC and AC behavior in LTSpice.

I've modified the netlist to remove these initial conditions, and the OPA192 model now seems to be working correctly. Please use this modified model until we're able to update the version that's released on the web.

Model download: OPA192_mod.cir

Here you can see the difference in a closed loop gain = +1 analysis between the existing model and the modified model. Vout_2 shows the correct response from the modified model.