• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 29 subscribers
  • Views 170 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TLV320AIC3254: Overflow in TI biquad coefficient calculator

Trevor Hsu
Genius 4435 points
Part Number: TLV320AIC3254

Hi 

Regarding the overflow flag for TI biquad coefficient calculator.

The following figure show the overflow flag set to N when the scale bar is set to 0dB.

If we increase the scale bar to 12dB, the overflow flag will change to Y, you could see the following figure:

We would like to use the Biquad filter to ADC, could you help to check / confirm what is the scale bar?

Is it related to ADC input amplitude level or ADC PGA gain(P0_R83_R84 ) ?

Thanks.

BR

Trevor

  • 0
    TI__Mastermind 28635 points

    Hi,

    This scale bar is not the ADC PGA gain, but a scaling factor for the BQ coefficient.

    This is just a filter tool and not tied to any device specific gain, but I'd recommend to use other tool like matlab/other off-the-shelf tool to generate the filter.

    Regards.

  • 0 in reply to pdjuandi
    Genius 4435 points

    Hi pdjuandi,

    Thanks for your reply, but we tried to adjust the scale bar, it doesn't affect the filter coefficients.

    The following thread that the scale bar seems to be used to test for overflow.

    Our application uses 5 biquad filters, and the overall response can easily lead to system overflow.(scale bar set to 1dB)

    If the input signal amplitude is large, we can probably encounter the out of band noise.

    If we try to redesign 5 biquad filters that are less prone to overflow (scale bar set to 4dB), the above out of band noise issue can reduce the chance of occurrence.

    So we want to check if the scale is related to the ADC input amplitude level.

    BR

    Trevor

  • 0 in reply to Trevor Hsu
    TI__Mastermind 28635 points

    Hi,

    This slider is a scaling factor to see if input signal with this factor will saturate and become unstable not necessary to set but as indicator with the filter design gain.

    Regards.