Editing Ring modulation (section)

== Circuit description ==
The ring modulator includes an input stage, a ring of four diodes excited by a carrier signal, and an output stage. The input and output stages typically include [[Transformer|transformers]] with center-taps towards the diode ring. While the diode ring has some similarities to a [[bridge rectifier]] the diodes in a ring modulator all point in the same clockwise or counterclockwise direction.

The carrier, which alternates between positive and negative current, at any given time makes one pair of diodes conduct, and [[P–n junction#Reverse bias|reverse-biases]] the other pair. The conducting pair carries the signal from the left transformer secondary to the primary of the transformer at the right. If the left carrier terminal is positive, the top and bottom diodes conduct. If that terminal is negative, then the side diodes conduct, but create a polarity inversion between the transformers. This action is much like that of a [[DPDT]] (''double pole, double throw'') switch wired for reversing connections.

A particular elegance of the ring modulator is that it is bidirectional: the signal flow can be reversed allowing the same circuit with the same carrier to be used either as a [[modulator]] or [[demodulator]], for example in low-cost radio transceivers.