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OPA197: Question about DC simulation

na na78
Guru 16770 points
Part Number: OPA197

Hi

I want to confirm OPA197 simulation model can offer correct behavior.

I attached file.

6278.e2e.xlsx

I tried simulation to see the impact of Vos and Ib.

Questions

1.

As a result, Figure 1 and Figure 2 shows same output level.

What is contributed with 236.49mV output?

2.

I obtained small output level in Figure 3. In figure 3, I changed power supply to +/- 10V.

Compared with Figure 1 or 2, is 215uV normal output?

BestRegards

  • 0
    Guru 140200 points

    Hi Na na,

    the output of OPA197 cannot fully go down to 0V when being supplied with a single supply voltage. The output voltage swing to the rails is limited. Please see section 6.7 of datasheet. That's why you see 236.49mV output voltage in figure 1 and 2 and why the output voltages aren't different in these figures.

    In figure 3 with the bipolar supply voltage, on the other hand, the OPA197 is in its linear range again and shows the input offset voltage multiplied by the set gain.

    So, everything is working as expected.

    Kai

  • 0
    TI__Genius 13140 points
    Hi Na na,
    Kai is correct. The test circuits in figure 1 and 2 of your spreadsheet model the output swing limitation of the OPA197, rather than its offset voltage. The output voltage in figure 3 is correct, corresponding to a Vos of 21.5µV gained up by 10x.