SLAA901 July   2020  – MONTH  TAS2555 , TAS2557 , TAS2559 , TAS2560 , TAS2562 , TAS2563 , TAS2564 , TAS2764 , TAS2770 , TAS2780 , TAS2781

 

  1. 1Trademarks
  2. 2Introduction
  3. 3Filter Design
    1. 3.1 Filter Cutoff Frequency Selection
    2. 3.2 Capacitance Only Filter Impact on Efficiency
  4. 4References

2 Introduction

The output from a Class-D amplifier consists of a PWM waveform that is typically resolved into a clean audio waveform by passing the signal through an LC filter to remove the high frequency portion of the output signal. Modern H-bridge amplifiers can operate without this filter by using the inductance to replace this filter. However, given the power levels typical to audio applications and the output switching frequencies required for this type of operation, a filter is often still necessary to meet electromagnetic emission standards. Many designers wish to use capacitive-only output filters given the small size and low cost required for these components, but this approach involves significant risk and it is not recommended for use on Class-D outputs.