An example might be the above schematic with the typical-mode choke and pair of capacitors linked to an op-amp. The transfer function from the amplifier can then be modified by including reactive elements for the feed-back loop, While Be careful for the stability of this sort of active EMI filter https://jee-class-12-physics80012.webbuzzfeed.com/31762411/the-fact-about-schaffner-emi-filter-that-no-one-is-suggesting