Editing Ring modulation (section)

== History ==
The ring modulator was invented by Frank A. Cowan in 1934 and patented in 1935<ref>{{US patent|src=uspto|2025158}}</ref> as an improvement on the invention of Clyde R. Keith at [[Bell Labs]].<ref>{{US patent|src=uspto|1855576}}</ref> The original application was in the field of [[Telephone|analog telephony]] for [[frequency-division multiplexing]] for carrying multiple voice signals over telephone cables. It has since been applied to a wider range of uses, such as [[voice inversion]], radio [[transceiver]]s, and [[electronic music]].

While the original Cowan patent describes a circuit with a ring of four diodes, later implementations used [[FET]]s as the switching elements.