SLAAED0 March   2024 TAS2764 , TAS2780 , TAS2781

 

  1.   1
  2.   Abstract
  3.   Trademarks
  4. 1 Introduction
  5. 2 Measurement Methodology
  6. 3 Introduction to Noise-gate and Pop in Class-D Amplifiers
  7. 4 Causes of Pop in TAS27xx family of Class-D Amplifiers
  8. 5 Click and Pop Using TAS27xx
  9. 6 Click and Pop Measurement Technique Using AP v6.0. 2
    1. 6.1  Measurement Setup
    2. 6.2  Filter Settings
    3. 6.3  Data Capture Settings
    4. 6.4  Auto Range Settings for Pop Measurement
    5. 6.5  ASI or I2S Configurations for Pop Measurement
    6. 6.6  APx Sound Level Meter Utility
    7. 6.7  Data Acquisition
    8. 6.8  Interpreting Click and Pop Waveforms
    9. 6.9  Post Processing of AP Waveforms
    10. 6.10 A-Weighted Click and Pop Numbers
    11. 6.11 Exporting the A-Weighted Numbers
  10. 7 Noise-Gate Pop and Measurement Technique Using APx
  11. 8 Configuring TAS2764 for Improved Click and Pop Noise Performance
    1. 8.1 Explanation
  12. 9 Summary
  13. 10References

6.2 Filter Settings

AP is configured with the filter settings as shown in Figure 6-2.

GUID-20231109-SS0I-JBBL-RFRR-BGP7LWZCFMND-low.png Figure 6-2 AP Filter Settings

High-Pass Filter (Elliptic 20Hz): 20Hz, 5-pole elliptic high-pass filter is chosen. The filter has a passband ripple of 0.01dB and a sharp roll-off to -60dB.

Low-Pass Filter (AES17 20kHz): This filter is an 8-pole elliptic filter with a corner frequency at 20kHz, satisfying the AES17 recommendation for converter measurements and other measurements in the presence of high out-of-band noise. When this filter is selected, the ADC sample rate is set to 48kHz.

Note: Elliptic filter is chosen over the Butterworth filter as the Elliptic filter has a better brick wall response compared to a Butterworth filter and offers more accurate representation of audio pop. Comparison of Elliptic and Butterworth Filter responses is given in Figure 6-3 and Figure 6-4 for reference.
GUID-20231109-SS0I-DHW0-CCWR-KXQ4VB5T845B-low.pngFigure 6-3 100Hz Elliptic Filter Response
GUID-20231109-SS0I-8GT0-9TVK-KW4SMVLZ2L5L-low.pngFigure 6-4 100Hz Butterworth Filter Response