主要介绍了锁相环的基本原理，PLL参数测试示例展示，重点分析了CD4046——通用的CMOS锁相环集成电路，MT8870——音调译码器(Tone Decoder)是MITEL 公司所开发生产为一颗常用复频译码IC。-Introduces the basic principles of phase-locked loop, PLL parameter test sample shows, analyzes the CD4046-- generic CMOS PLL IC, MT8870-- tone decoder (Tone Decoder) is MITEL company developed and produced for a common stars complex frequency decoding IC.