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

3 Introduction to Noise-gate and Pop in Class-D Amplifiers

Past literature studying the audibility of click and pop to the human ear clearly show that pop is an perceptible artifact and hence is critical to minimize the same (Reference: Click and Pop Measurement Technique). Since click and pop noise voltage can be played across the speaker, and hence perceptible to the user. Achieving low pop is critical for best user audible experience.

In TAS27xx family of amplifiers there exists a noise gate feature (NG) (8.4.2.7 on TAS2780 data sheet), in which the Class-D amplifier is dynamically shutdown and turned back on based on the audio input received. For example, if the Noise gate threshold is set to -120dBFs the Class-D automatically shuts down if the audio input to the device remains lower than this threshold for >50 ms (NG hysteresis time) duration. The moment an audio sample greater than the NG threshold is received by the device, the device automatically exits NG and the Class-D amplifier immediately turns on to play the corresponding sample faithfully at the Class-D output. This feature allows for improved amplifier efficiency for audio profiles where there are long durations of silence. Consequently, since repetitive shutdown of the amplifier happens during entry and exit from noise gate, it is further important that click and pop noise remain low.