Electromagnetic interference suppression in power converters

A switching power supply, comprising:

• a rectifier having input terminals and output terminals, wherein the input terminals of the rectifier are electrically coupled to AC supply input terminals;
• a DC-DC converter having input terminals;
• and
• an active choke circuit electrically coupled between the output terminals of the rectifier and the input terminals of the DC-DC converter, wherein the active choke circuit comprises:
• a first three-winding choke;
• a second three-winding choke;
• and
• an amplifier;
• wherein a first winding of the first three-winding choke is electrically coupled in series with a first winding of the second three-winding choke;
• wherein a second winding of the first three-winding choke is electrically coupled in series with a second winding of the second three-winding choke;
• wherein a third winding of the first three-winding choke is electrically coupled to an input of the amplifier;
• and
• wherein a third winding of the second three-winding choke is electrically coupled to an output of the amplifier.