LC Filter Design (Rev. A) TI（LC滤波器设计(启) TI）.pdf

Application Report SLAA701A– October 2016– Revised November 2016 LC Filter Design ABSTRACT In higher-power class-D amplifiers, generally above 10 W of output power, a filter on the output of the amplifier is required. The filter is passive in nature and uses both an inductor and a capacitor on each output terminal. Therefore, it is referred to as an LC filter. Proper component selection of the LC filter is critical to meet the desired audio performance, efficiency, EMC/EMI requirements, and cost for the end application. This application report serves as a guide to aid in the section of LC filter components for class-D amplifiers to meet target-design goals of the end system. Contents 1 Class-D Output Configurations 3 1.1 Bridged-Tied Load (BTL) 3 1.2 Parallel Bridge-Tied Load (PBTL) 3 1.3 Single-Ended (SE) 4 2 Class-D Modulation Schemes 5 2.1 AD (Traditional) Modulation 5 2.2 BD Modulation 6 3 Class-D Output LC Filter 7 3.1 Output LC Filter Frequency Response Properties 7 3.2 Class-D BTL Output LC Filter Topologies 8 3.3 Single-Ended Filter Calculations 9 3.4 Type-1 Filter Analysis 1