US 9,794,001 B2 · Optical receiver with multiple transimpedance amplifiers

Abstract

A method and system for amplifying small optical currents in an optical receiver front end system may employ multiple transimpendance amplifiers (TIAs) and feedback control loops. For example, the front end system may include a main feedback control loop (having a main TIA) and a replica feedback control loop (having a replica TIA) that, collectively, generate an optimum input common mode level for a differential amplifier operating at high data rates (e.g., speeds up to tens of gigabits per second). The replica TIA may track the noise from the power supply of the optical receiver in the substantially same manner as the main TIA. Therefore, the differential signals produced by the main control loop may not be degraded at the input to the high-speed differential amplifier. The outputs of the high-speed differential amplifier may be symmetric about the common mode level and may be suitable inputs for voltage sampling.

Claims17

Dependent claims

An optical receiver, comprising:

a photo detector to convert an optical signal into a first electrical current signal;
a transimpedance amplifier, included in a main feedback control loop, to:
receive, as input, the first electrical current signal;
and
output a first voltage signal having a first DC component;
a replica transimpedance amplifier to:
receive, as input, a second electrical current signal;
and
output a second voltage signal, wherein the first DC component of the first voltage signal and a second DC component of the second voltage signal are substantially equal;
and
a first differential amplifier to:
receive, as inputs from the transimpedance amplifier and the replica transimpedance amplifier, the first voltage signal and the second voltage signal, respectively;
and
output a pair of output voltage signals that are symmetric about a common mode voltage,
the main feedback control loop comprising a third differential amplifier to:
receive, as input signals, the pair of output voltage signals output by the first differential amplifier;
and
amplify the received input signals.

15 more elements

A method of designing an optical receiver, the method comprising:

designing an inverter-based resistive feedback amplifier;
designing a first differential amplifier to operate at data rates up to multiple gigabits per second;
designing a second differential amplifier to operate at data rates lower than those at which the first differential amplifier operates;
designing a third differential amplifier to operate at data rates lower than those at which the first differential amplifier operates;
designing a feedback control loop comprising the inverter-based resistive feedback amplifier, the first differential amplifier, and the second differential amplifier;
and
designing a replica feedback control loop comprising a replica of the inverter-based resistive feedback amplifier and the third differential amplifier;
wherein an output of the inverter-based resistive feedback amplifier and an output of the replica of the inverter-based resistive feedback amplifier are inputs to the first differential amplifier;
and
wherein the feedback control loop is designed such that, once settled, it causes the output of the inverter-based resistive feedback amplifier to follow the output of the replica of the inverter-based resistive feedback amplifier,
the designing the replica feedback control loop comprises:
choosing a common mode selector reference voltage for input to the third differential amplifier;
and
the replica feedback control loop is designed such that, once settled, it causes a common mode voltage of the output of the replica of the inverter-based resistive feedback amplifier to match the common mode selector reference voltage.

11 more elements

Dependencies are inferred from the claim text.

Optical receiver with multiple transimpedance amplifiers

Life of this patent

Optical receiver with multiple transimpedance amplifiers

Life of this patent

Abstract

Claims17