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Notch filter needed before 16 TLV320AIC14K CODECs

Jorge Miguel
Expert 1020 points
Other Parts Discussed in Thread: TLV320AIC14K, PCM1870A, TLV320AIC3204

 

Hello,

I need to capture 16 differential audio channels and transmit them in a single bus (an FPGA will read that bus). I think TLV320AIC14K is perfect since I can cascade 16 ICs so that I get the 16 channels in a single bus by using the SmartTDM feature.

However I need to remove a non-desired component at 2280Hz (which is line signalling that has to be hardware removed). Since 2280Hz is within the audio BW I thought of a notch filter before each TLV320AIC14K CODEC.

How can I proceed which the notch filter? a switched capacitor filter? an op-amp IC? (I need a very selective filter).

I also realized that other CODECs can notch filter such us PCM1870A but they don't have SmartTDM feature (and it is very convenient for me).

Many thanks for your help in advance

  • 0
    Expert 1020 points
    Hello,

    Something I forgot to mention is that the audio signal is differential, so the notch filter should be differential input/output.

    Thanks in advance
  • 0 in reply to Jorge Miguel
    TI__Guru* 84915 points
    Hi, Jorge,

    Unfortunately, we don't have a codec with SMARTDM and notch filter. However, we have several codecs that supports TDM function which can be configured with a notch filter.

    You may take a look at the TLV320AIC3204. It is an ultra low power stereo audio codec with ADC/DAC processing blocks that can be programmed for notch filter function (user-programmable filters).

    Please let me know if you have more questions or comments.

    Best regards,
    Luis Fernando Rodríguez S.
  • 0 in reply to Luis Fernando Rodriguez S.
    Expert 1020 points
    Hello Luis Fernando,

    TLV320AIC3204 looks good as a CODEC. However I can read on the datasheet that the IC always has the same I2C address so that 16 devices in a single I2C bus are not supported.

    The only option would be SPI configuration and it would require 16 SS lines plus MISO, MOSI and CLK going into all of them. The routing of that gets uglier than the I2C option...
    How can I see the selectivity of the possible notch filter implemented in the IC ?

    When using the TLV320AIC14K CODEC, would you recommend some particular hardware filter before the CODEC?

    Many thanks for your help,
  • 0 in reply to Jorge Miguel
    TI__Guru* 84915 points

    Hi, Jorge Miguel,

    Please, take a look at the following document: http://www.ti.com/lit/an/slyt235/slyt235.pdf. It should be useful for your application.

    Let me know if you have more questions or comments.

    Best regards,
    Luis Fernando Rodríguez S.