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TINA/Spice/OPA2171: OPA2171 Phase margin

Midhun M
Prodigy 230 points
Part Number: OPA2171
Other Parts Discussed in Thread: TINA-TI, , OPA171

Tool/software: TINA-TI or Spice Models

Hi,

What is the unity gain Phase margin for OPA2171.

Can you share the test circuit for opamps open loop response.

With the spice model provided, unity gain is observed at 3.2MHz and phase margin of 82 considering RL=10K and CL=100p

Thanks

Midhun

  • 0
    TI__Intellectual 2550 points

    Hello Midhun!

    The unity gain phase margin for the OPA2171 in an open loop response configuration is approximately 50°. You can review the simulation in the attached TINA Schematic. 

    Please let me know if there is anything else you may need.

    Regards, 

    Ramon Jimenez

    General Purpose Amplifiers

    OPA2171 Open-Loop Response CKT.TSC

  • 0 in reply to RJ
    Prodigy 230 points

    Hi Ramon,

    Thank you.

    There is no load considered here in the circuit, normally R C load will be used to define the loop response.

    The latest spice model dated 17th Jan 2017 seems to be different from the model you have shared.

    Regards,

    Midhun

  • 0 in reply to Midhun M
    TI__Intellectual 2550 points

    Hi Midhun,

    Adding a capacitor and resistor to the output and measuring its response will provide the information you are looking for, but may introduce stability issues. For more information on this you can view the TI Precision Labs Videos on stability.

    There may be an error with that model though, and I have noted it down here with the team. It is something that we will work on to update and release in the future. Could you share what you have with me so I can verify the model?

    For now I'd recommend using the TLV171 model for your testing purposes, as it has the same output stage configuration as the OPA171 for AC analysis. Also, if you could share your circuit with me, I could better assist you. Is this something you can do? 

    Regards,

    Ramon Jimenez

    General Purpose Amplifiers