一种具备高镜像抑制比的带通滤波器设计

摘要

介绍一种高镜像抑制比的带通滤波器的设计。在音频领域里所接触的大多为实数滤波器，滤波器的频率点具备对称性的特点，这就对信号处理领域带来很大的麻烦，如AM、FM中频滤波时产生的镜像频率，会对正常的搜台产生很大的干扰。此设计利用复数滤波器的特点，设计出一种具备高镜像抑制比的带通滤波器，应用于数字调谐收音机解调系统里面。由于采用的是全集成的复数带通滤波器，节省了传统的外部中频滤波器的成本及空间；实测镜像抑制比达40 dB，大大降低了搜台的误操作，提高了整机系统的信噪比，在信号处理领域有一定的借鉴意义。%The paper introduces a design of bandpass filter with high image rejection ratio. In the audio field, we contact mostly real filter, this filter have the characteristics of symmetry, which will bring the field of signal processing to a lot of trouble, such as the mirror frequency to produce AM, FM intermediate frequency filtering, will have a lot of interference to the channel search normal, this design uses the characteristics of complex filter, design a rejection bandpass filters with high image rejection ratio, it’s used in digital tuning radio demodulation system, due to the use of the fully integrated bandpass filter, saves cost and space outside of the traditional intermediate frequency filter; inhibition ratio of 40 dB image rejection, greatly reduces the error operation channel search, improves the signal-to-noise ratio of the system, has certain reference meanings to the field of signal processing.