开关电源对车载收音机AM信号干扰的研究

Study on the Interference of Switching Power Supply to the AM Signal of Car Radio

车载收音机主要包括收音和开关电源等模块,国内收音AM的频率范围为531~1 629 k Hz,目前开关电源芯片的开关频率一般为几百千赫兹。当开关电源的工作频率或者其2~3倍工作频率恰好在收音频段,则开关电源的开关噪声会干扰收音信号,从而影响收音效果。因此,在选择和设计开关电源的频率时,需考虑将开关频率调到其他频率,从而避免其对AM搜台的影响。提出一种针对AM频段不同频点而采用电源不同开关频率的方案来解决开关电源对当前AM信号干扰的难题。

The car radio includes radio module and switching power supply module. The frequency range of domestic radio AM is 531 - 1 629 kHz and the switching frequency of the switching power supply chip is generally several hundred kHz. If the switching power supply＇ s working frequency or its two or three times working frequency are just in the radio band, the switching noise will interfere the radio signals. Therefore, when selecting and designing switching power supply, it is necessary to consider the switching frequency , so as to avoid the influ- ence to AM signal. A scheme was put forward to solve the interference problem of switching power supply to the AM signal, which was based on the different frequency points of the AM and the different switching frequency of the power supply.