• State Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 1 answer
  • Subscribers 30 subscribers
  • Views 1080 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

PGA2320: Gain error

user661510
Prodigy 130 points
Part Number: PGA2320

  • 0
    TI__Mastermind 49405 points

    Hello Jimmy,

    The typical gain error of the PGA2320 at Gain setting of 31.5dB is approximately ±0.1dB on the frequency range of 20Hz -20kHz; please note this is not a maximum guaranteed specification. In the application, you are measuring -0.131dB; which is close to the expected typical gain error specification.

    When calculating the gain error, are you measuring both the input signal and output signal right at the input pins and output pins of the PGA2320 amplifier for each frequency and gain setting?  This will ensure you remove any effects ofother components in your circuit.

    Best Regards,

    Luis

     

  • 0 in reply to Luis Chioye
    Prodigy 130 points

    Hi, Luis Chioye 

    Thank you for answer.
    I know what's on the datasheet. If my gain accuracy calculation is wrong, there should be an error at 0dB.

    Therefore, the gain error calculation is not wrong and it will not be affected by other circuits.

    If the measurement data or the part of the data sheet does not specify the part where the error may occur as the gain increases, the user will ask about what to see and select.

    Best Regards,

    Jimmy.

  • 0 in reply to user661510
    Genius 3945 points
    Jimmy,

    You didn't actually answer Luis's question about how you went about your specific measurement.

    Also, the ADA4940 is an interesting choice for an audio-frequency differential amplifier/ADC driver. Did you follow Analog Devices' layout suggestions?
  • 0 in reply to Andy Peters
    TI__Mastermind 49405 points

    Hello Jimmy,

    Unfortunately, I do not have data immediately available of the gain error at 30dB vs frequency; this device was developed in 2004.

    I will continue search for data, and also look into performing bench measurements using the Audio Precision.  It will take a couple of days and have the bench system setup in place.  I expect to have data by early/mid next week.

    Best Regards,

    Luis

  • 0 in reply to Andy Peters
    Prodigy 130 points
    Hi peters

    In the past, I had a lot of answers when I asked the PGA2320 gain control question. nice to meet you. I did not answer Luis's question because there was no error at 0dB. If it was a problem with the back-end circuit, it should have the same characteristics at 0dB. It is very likely that PGA2320 is a characteristic in view of the increase in error as the gain increases. What about Peter's thoughts?

    Best Regards,

    Jimmy.
  • 0 in reply to user661510
    TI__Mastermind 49405 points

    Hello Jimmy,

    Measured the Gain Error of a fresh sample of the PGA2320 with Gain = 0dB and Gain =30dB at a few points between 100Hz and 5-kHz.The input signal was Vin=6-Vrms for Gain=0dB, and Vin=0.1892-Vrms for Gain=+30dB.  The gain error measurements were made using the Audio Precision AP555.

    The frequency response at Gain=0dB looks almost flat, and at Gain=30dB there is a subtle attenuation as frequency increases; although the attenuation is small, a -0.030dB change in gain error from 100Hz to  5-kHz at G=30dB for both channels. Verified the input signal amplitude and output signal amplitude at each frequency right at the inputs/outputs of the PGA2320.

    Please see below.

    Best Regards,

    Luis