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TINA/Spice/THS4631: Open-Loop Gain and Phase

Sam Massmann
Prodigy 20 points
Part Number: THS4631
Other Parts Discussed in Thread: TINA-TI,

Tool/software: TINA-TI or Spice Models

Has anyone been able to recreate (in simulation) the Aol plot (figure 12) from the THS4631 datasheet? If so, what method did you use?

I've tried a few common methods for finding Aol, including those described in TI's "Solving Op Amp Stability" presentations, but the open loop gain plot from the SPICE model seems way off.

Thanks.

  • 0
    TI__Genius 9775 points
    Hi Sam,

    Are you referring to the DC gain or the Gain Bandwidth Product (GBWP)?

    Yes, I notice the DC gain seems to be a bit off, but the GBWP is about the same as the datasheet. Generally speaking the discrepancy in the DC gain will not affect stability as long as GBWP is about the same as the datasheet.

    Herman
  • 0 in reply to Herman Theodorus
    Prodigy 20 points

    Hi Herman,

    Thank you for the reply.

    Yes, the datasheet is showing a flat DC gain of 80dB up to ~5kHz, but the model does not have this pole near 5kHz.

    The pole is all the way down near 0.1Hz, where the gain is ~160dB.

    I agree, the GBWP looks correct, and this is more important for stability. It is just a bit unsettling to see such a large difference in the datasheet and the simulation.

    Thanks,

    Sam