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PCM2906: PCM2906

John Melrose
Prodigy 20 points

Part Number: PCM2906

Hello,

i have a question concerning the ADC sampling rate of the USB stero audio codec PCM2906.

According to the data sheet, the ADC DIGITAL DECIMATION FITLER FREQUENCY RESPONSE goes up to 32 times the sampling frequency, which i understand as half the operating frequency of the digital filter.

This would result in a sampling frequency of about 3 MHz. Is this really the case?

Thanks in advance!

John

  • 0
    TI__Guru 57800 points

    Hi, John,

    Welcome to E2E, Thanks for your interest in our products!.

    The information for either digital filter and decimation filter is referenced to the audio sampling rate. The maximum sample rate this part accepts is 48KHz, so in this case, the digital decimation filter will have a cut frequency of about 24KHz. 

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    Prodigy 20 points

    Hello Diego!

    thank you very much for your reply.

    I know that the decimation filter has its cut-off frequency @ about 24 kHz, if the audio sampling rate is 48 kHz.

    But i want to know the sampling rate BEFORE the decimation filter. A decimation filter is usually used to lower the sampling rate from a higher initial sampling rate.

    In my previous post i was referring to the decimation-filter-frequency-response on page 15 of:

    http://www.ti.com/lit/gpn/pcm2906

    The first figure on that page suggests, that the analog audio signal is initially captured with 64 times fs, resulting in 64*48000 Hz = 3.072 MHz.

    I just want an acknowledgement that this is true.

    Any help is appreciated!

    Best regards

    John