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OPA2189: OPA2189 compare ADA4610-2 used to AC source application

Jimmy WANG
Expert 2885 points
Part Number: OPA2189
Other Parts Discussed in Thread: OPA2197

Hi teams,

My customer original use ADA4610-2 on compensation topology. Application is AC source.

But the test results THD worse than ADA4610-2.So could you provide a better suggestion to replace ADA4610-2? 

Thanks!  

  • 0
    TI__Guru* 93105 points

    Hello Jimmy,

    You mention receiving worse THD from the OPA2189, than you had with the AD4610-2. I am a bit surprised that is the case. You don't mention the conditions in which the op amp is operating so it is difficult to know for certain why that is the case. The OPA2189 uses a auto-zero architecture to achieve extremely low voltage offset and drift, and it appears the AD4610-2 uses a conventional, non-switching architecture. The OPA2189 using an autozero architecture can be  sensitive to high impedances in the circuit where it is used. If that is the case, it can produce chopping artifacts that would appear in the frequency spectrum reducing the THD+N. I would have to see your circuit schematic to determine if that is a possibility.

    I suggest testing the OPA2197 e-trim, precision op amp in your ac current application. It doesn't use chopping, or auto zero technology to achieve very low voltage offset and drift. It is rated with very low total harmonic distortion + noise (THD+N) of 0.00008%, for G = 1, f = 1 kHz, and VO = 3.5 VRMS. You can view the OPA2197 datasheet here:

    www.ti.com/.../opa2197.pdf

    Let us know if that improves the THD.

    Regards, Thomas

    Precision Amplifiers Applications Engineering

  • 0 in reply to Thomas Kuehl
    Expert 2885 points

    Hi Thomas,

    Maybe my description ley you misunderstanding, the THD is mean AC source output waveform through power meter to get it.

    My customer use ADA4610 and OPA2189 to compare and get differnet THD result.

    So, Do you suggest OPA2197 to test again? maybe test result could be improved . 

  • 0 in reply to Jimmy WANG
    TI__Guru* 93105 points

    Hi Jimmy,

    We would need to see the circuit diagram and equipment used to make the distortion measurement, and also an image of the distortion to make a more conclusive assessment. But I do think that you should try the OPA2197 in the circuit and see if the distortion then meets the performance requirements of the system.

    Regards, Thomas

    Precision Amplifiers Applications Engineering