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Original question:

TLV320ADC3101: apply dither control to remove idle tone

TLV320ADC3101: question for dither control

Angela
Prodigy 50 points
Part Number: TLV320ADC3101

Hi,

We have use the dither control (dc offset +/-15mV) to remove the idle tone. And also, we have add a HPF (IIR filter) to reduce the DC component causing by the dither control.

There are some questions I would like to ask:

1. Adding dither control means add a dc offset to the input signal, given into a delta sigma ADC converter?

2. Will adding dither control and a HPF cause any side effect, like frequency response, SNR and THD+N performance?

3. For dither control, how much DC offset should I add to push out the idle tone?  Is there any information about the relationship between idle tone frequency and DC offset?

thank you.

Angela

  • 0
    TI__Genius 13610 points

    Hello Angela,

    I see your question and will respond by week's end.

    Thanks,

    Carson

    Low Power Audio Applications

  • 0 in reply to Carson Allen
    Prodigy 50 points

    Hi Carson,

    Any  update?

    thank you.

    Angela

  • 0
    TI__Genius 13610 points

    Hello Angela,

    In the context of this device dither just adds in a DC-offset

    Adding in DC-offset will reduce overall dynamic range and raise noise floor, which could affect SNR depending on size of signal being sampled.

    Idle tone is a sort of noise that is produced by the system itself with how voltage is sampled and patterned before going to decimation filter. When DC offset is added that pattern gets changed in a way which reduces pilot tone, it is not well documented how linear the relationship is but the larger DC value the less pilot tone you will get but that will also lessen dynamic range and raise noise floor, so there is a give or take that depends on application of system.

    Dithering is actually more than just a DC offset it is supposed to be uncorrelated noise added to combat idle-tone and avoid aliasing but that is very complicated and it is best understood by googling it for yourself.

    Best Regards,

    Carson

  • 0 in reply to Carson Allen
    Prodigy 50 points

    Hi Carson,

    Thanks for your help.

    Angela