International Business Machines Corporation

Matthew B Frank

Raymond Alan Richetta

Jonathan E Proesel

A method and circuit are provided for implementing enhanced CMOS inverter based optical Transimpedance Amplifiers (TIAs). A transimpedence amplifier (TIA) includes a photo-detector, and the TIA is formed by a first TIA inverter and a second TIA inverter. The first TIA inverter has an input from a cathode side of the photo-detector and the second inverter has an input from an anode side of the photo-detector. A replica TIA is formed by two replica inverters, coupled to a respective input to a first operational amplifier and a second operational amplifier. The first operational amplifier and the second operational amplifier have a feedback configuration for respectively regulating a set voltage level at the cathode side of the photo-detector input of the first inverter and at the anode side of the photo-detector input of the second inverter.

Implementing enhanced CMOS inverter based optical transimpedance amplifier

A method and circuit are provided for implementing enhanced CMOS inverter based optical Transimpedance Amplifiers (TIAs). A transimpedence amplifer (TIA) includes a photo-detector, and the TIA is formed by a first TIA inverter and a second TIA inverter. The first TIA inverter has an input from a cathode side of the photo-detector and the second inverter has an input from an anode side of the photo-detector. A replica TIA is formed by two replica inverters, coupled to a respective input to a first operational amplifier and a second operational amplifier. The first operational amplifier and the second operational amplifier have a feedback configuration for respectively regulating a set voltage level at the cathode side of the photo-detector input of the first inverter and at the anode side of the photo-detector input of the second inverter.

A dark photodiode that is optically isolated from the signal photodiode and having a dark current in the absence of photons. A reference generating circuit configured to produce a reference voltage based on voltage at an anode of the signal photodiode. A voltage regulator circuit configured to regulate dark photodiode voltage at an anode of the dark photodiode based on the reference voltage. A current mirror circuit configured to produce, at an anode connecting to the signal photodiode, a mirrored current that is a mirrored version of a portion of the dark current.

Offset current compensation for photodiodes

Implementing enhanced CMOS inverter based optical transimpedence amplifier

A method and circuit are provided for implementing enhanced CMOS inverter based optical Transimpedance Amplifiers (TIAs). A transimpedance amplifier (TIA) includes a photo-detector, and the TIA is formed by a first TIA inverter and a second TIA inverter. The first TIA inverter has an input from a cathode side of the photo-detector and the second inverter has an input from an anode side of the photo-detector. A replica TIA is formed by two replica inverters, coupled to a respective input to a first operational amplifier and a second operational amplifier. The first operational amplifier and the second operational amplifier have a feedback configuration for respectively regulating a set voltage level at the cathode side of the photo-detector input of the first inverter and at the anode side of the photo-detector input of the second inverter.

A method and circuit are provided for implementing an enhanced bias configuration for CMOS inverter based optical Transimpedance Amplifiers (TIAs). An operational amplifier is provided in a feedback configuration that forces an input of the CMOS inverter to a set voltage level by regulation of the inverter power supply. A photo-detector sees a more stable bias voltage, and the responsivity of the photo-detector is more robust and the TIA has improved performance across process corners.

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Rochester, MN, United States of America

Matthew B Frank