Differential transimpedance amplifier from a single photodiode

An optical-electrical apparatus, comprising:

• a photodiode having an anode terminal and a cathode terminal;
• a cathode biasing circuit connected to the cathode terminal;
• and
• a differential transimpedance amplifier configured to receive, at a first input terminal, a current from the cathode terminal and convert the received current to a first output voltage, wherein the cathode biasing circuit is configured to bias the cathode terminal at a high operating voltage of the optical-electrical apparatus and provide an impedance greater than a combined impedance of an impedance at the first input terminal and at a level shifter connected between the cathode terminal and the first input terminal, wherein the level shifter:
• is configured to shift a cathode terminal voltage at the cathode terminal to a lower input voltage at the first input terminal;
• and
• includes a parallel RC circuit and a current dump circuit configured to control a current through a resistor of the parallel RC circuit to shift the cathode terminal voltage to the lower input voltage at the first input terminal.

An integrated circuit, comprising:

• input interface;
• and
• an optical receiver including:
• a photodiode, having a cathode terminal and an anode terminal, configured to receive an optical signal via the input interface;
• a level shifter including a parallel RC circuit;
• and
• a differential transimpedance amplifier having a first conversion circuit connected to the cathode terminal and a first output terminal of the optical receiver and a second conversion circuit connected between the anode terminal and a second output terminal of the optical receiver, wherein the parallel RC circuit is connected between the cathode terminal and the first conversion circuit and the differential transimpedance amplifier is configured to provide a differential voltage signal at the first and second output terminal based on the optical signal, wherein the level shifter further includes a sensing loop having a sensing operational transconductance amplifier (OTA) and an output transistor, wherein either a first input terminal pair of the sensing OTA is connected to negative terminals of the first and the second conversion circuit, a second input terminal pair of the sensing OTA is connected to positive terminals of the first and the second conversion circuit, or both and an output of the OTA is connected to a gate of the output transistor.

A library of circuit designs, comprising:

• an optical receiver, the optical receiver comprising:
• a photodiode having a cathode terminal and an anode terminal;
• a level shifter including a parallel RC circuit;
• and
• a differential transimpedance amplifier having:
• a first conversion circuit connected to the level shifter and a first output terminal of the optical receiver, wherein the parallel RC circuit is connected between the cathode terminal and the first conversion circuit;
• and
• a second conversion circuit connected between the anode terminal and a second output terminal of the optical receiver, wherein the first and the second conversion circuits are different circuits and the first and the second output terminals are separate terminals, wherein the level shifter of the optical receiver further includes a sensing loop having a sensing operational transconductance amplifier (OTA) and an output transistor, wherein either a first input terminal pair of the sensing OTA is connected to negative terminals of the first and the second conversion circuit, a second input terminal pair of the sensing OTA is connected to positive terminals of the first and the second conversion circuit, or both and an output of the OTA is connected to a gate of the output transistor.