Postdistortion circuit for reducing distortion in an optical communications system

Claim 1

A postdistortion network for a receiver at a receiver location in an optical communications system, said receiver converting an optical signal carried over the optical communications system to an RF signal, said postdistortion network comprising: an input terminal for receiving the RF signal; a distortion generator for generating a distortion signal from the RF signal; adjusting means for adjusting the phase and amplitude of the distortion distortion at said receiver location; and combining means for combining the adjust distortion signal with the RF signal to cancel or substantially suppress distortion in said RF signal, wherein said distortion generator comprises a distortion generator for generating third order distortion, and wherein said distortion generator for generating third order distortion comprises: a directional coupler having a first port for receiving said RF signal and coupling a portion of said RF signal to a third port; a diode circuit for generating said third order distortion and including a first diode having an anode coupled to said third port and a cathode coupled to a reference potential and a second diode having a cathode coupled to said third port and an anode coupled to the reference potential, wherein said distortion generated by said diode circuit is output at a second port of said directional coupler.