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AGC

Jesper Gormsen Kragh
Prodigy 220 points
Other Parts Discussed in Thread: PCM3070

Hi All

Designing AGC functionality for the PCM3070 In the PPS (Home Audio), give me two different AGC solutions.

I can use the AGC part of the Decimator, by editing the runtime properties of the decimator, and use a separate AGC block found under "dynamic processing".

Could i ask you to elaborate on the differences btw the two blocks ?

I see in the datasheet that the AGC will operate the analog gain stage prior to the decimator.

I assume that the "Decimator AGC" will operate on the analog PGA, and that the separate AGC block is purely digital. Is this correct ?

Finally PPS seems only to support "Decimator AGC" on both channels simultaniousley. I would like to use it only on one channel. Can i simply enable the "Decimator AGC" and then disable it for one channel simply by overwriting the I2C register for the channel manually (Page 0 bit 7 of either Reg 86 or 94) ?

Thanks in advance

BR

Jesper

  • 0
    TI__Guru**** 189401 points

    Hi, Jesper,

    Did you get this figured out?

    I am going to move this post to the audio converter forum for you.

    -d2

  • 0 in reply to Don Dapkus
    Prodigy 220 points

    Hi Don

    Still open.

    Product launch end Q1, so need to focus on the issue during Feburary.

    Thanks for moving to right forum. Hope for inpts.

    :>) BR

    Jesper

  • 0
    TI__Intellectual 2810 points

    Jesper, this response is from our software team:

    There are two AGC’s available for the PCM3070.  One is controlled via the decimator properties and is implemented via a hardware accelerator.  The gain associated with this AGC is applied to both the PGA (hardware) as well as the in the decimator (software). The second AGC is a software implementation that is available as a component in the palette.  This AGC provides a higher resolution log calculation, but also requires more software resources.

    You are correct in your statement regarding the decimator AGC operating on the analog PGA and the separate AGC block is purely digital.

    Regarding the AGC implemented via the decimator, if you require two channels (i.e. stereo decimator), the AGC gain is applied to both channels when enabled.  I will check further on disabling the decimator AGC for one channel. I believe these bits disable the AGC application to both HW and SW, but will verify it.  I tested disabling the AGC in one channel and it does appear to disable the AGC in the one channel.  Again, I will verify the operation of these bits.

    The software AGC can be implemented as either a mono or stereo component and could be applied to only one channel.  

    Regards,

    Andrew Kling