Optical receiver circuit

A circuit for coupling the AC component of an input signal across a first and second input terminal to the input of a preamplifier adapted for receiving said input signal comprising:

• said first input terminal coupled through a first capacitor to a first output terminal,
• said second input terminal coupled through a second capacitor to a second output terminal,
• a first resistor having one end coupled to said first input terminal and its other end adapted for coupling to a first voltage supply,
• a second resistor having one end coupled to said second input terminal and its other end adapted for coupling to a second voltage supply,
• first means for detecting the voltage on said first terminal and for supplying a first current in response thereto to said first terminal and for supplying a first mirror current, substantially equal to said first current, to said second output terminal,
• second means for detecting the voltage on said second terminal and for removing a second current in response thereto from said second terminal and for removing a second mirror current, substantially equal to said second current, from said first output terminal,
• third means for detecting the average voltage on said first terminal and for supplying a third current in response to the average voltage on said first terminal to said first output terminal, and
• fourth means for detecting the average voltage on said second terminal and for removing a fourth current in response to the average voltage on said second terminal from said second output terminal.

An optical receiver circuit for receiving optical signals comprising:

• a photodetector having a first and second terminal,
• said first terminal coupled through a first capacitor in a first input of a transimpedance amplifier,
• said second terminal adapted for coupling to a voltage source,
• first means for detecting the voltage on said first terminal and for removing a first current in response thereto from said first terminal, and
• second means for detecting the voltage on said first terminal and for supplying a second current to said first input indicative of the AC component of said voltage on said first terminal whereby the output of said transimpedance amplifier provides a signal indicative of the AC voltage on said first terminal.