关于斩波放大器

super成

在一篇关于斩波放大器的论文中看到这样一句话“The conventional chopper amplifier needs a higher cutoff frequency than fchop”“To prevent attenuation of input signal which be converted to fchop, the cutoff frequency of chopper amplifiers should be higher than the chopping frequency,”怎么理解截止频率和斩波频率的关系？

woodhorse

输入信号最高频率fs,chop频率fc,那么放大器要处理的最高信号频率是fc+fs， 所以cutoff频率当然要高于fc了。

黄礼茉

回复 2# woodhorse


   比如一个三级运放，在第一级前后加chopper，那么就是要求第一级的cutoff frequency 高于fchop+fsignal,这样理解对么？

snola

First, the chopper frequency must higher than the input frequency to modulate the offset to the high-frequency domain. Second, the cut-off frequency of the low pass filter is used to decide the effect of fitting modulated offset signal to DC. Finally, the offset is disappeared. Hence, the relationship of chopper frequency and the input signal is needed to concern the cut-off frequency to avoid reduce the swing of output.