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PCM1681: Group delay

user6007935
Prodigy 10 points
Part Number: PCM1681
Other Parts Discussed in Thread: PCM4104,

Hi 

Looking in the datasheet for PCM1681 I cannot find information about group delay. If I look at another device like PCM4104 it is clearly stated in the datasheet.

So what is the group delay in PCM1681?

Thanks

  • 0
    TI__Guru 54643 points

    Hi,

    I think this is an issue in a lot of datasheets.  I have seen the term "group delay", "filter delay", and "time delay" used interchangeably. Really, group delay is more of a curve than a single number.  My understanding of group delay is that is it is the derivative of the phase delay of the digital filter, so not really a parametric at all. 

    The term used in the PCM1681 is filter "time delay", which I think is a better name.  Basically, what we are saying is that if you put in a sine-wave signal and monitored the I2S data and analog output, you would see about 24 sample periods between the peak data and the peak output.  

    This is what the "group delay" spec in the PCM4104 is trying to convey as well. 

    So to answer your questions, you are looking at 24/fs for the PCM1681 and 29/fS for the PCM4104.

    Thanks,

    Paul