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

2 Measurement Methodology

Pop is effectively quantified as an output peak voltage that gets played across the speaker before settling of the amplifier output, during power-up and power-down. Since the audio band energy (20-20KHz) at Class-D output is only of interest, there are audio band pass filters used at the Class-D output used for measurement. Further an A-weighting filter, which is used to mimic the human ear response, is cascaded with these preceding filters.

GUID-20231109-SS0I-RPZ0-7KPS-78QWCPQJDF5G-low.png Figure 2-1 Pop Measurement

The measured pop is quoted as a voltage across the speaker (either in mV or dBV).

For example, 1mV pop refers to -60dBV click and pop:

Equation 1. 20 * l o g 10 ( l e - 3 )   =   - 60 d B V

The typical click and pop performance measured on TAS2780, for example, is 0.8mV or -62dBV (Referred to as Kcp in Electrical Characteristics section 6.5 of data sheet)

Figure 2-2 shows the measured Class-D output waveform and measured pop due to PWM start and stop.

GUID-20240312-SS0I-GMFC-TVHX-TRVJNLZM9KZQ-low.png Figure 2-2 Measured Pop Due to Start and Stop of Class-D PWM