US 2022/0090963 A1 · DIFFERENTIAL TRANS-IMPEDANCE AMPLIFIER RECEIVER USING COUNTER-OFFSET CIRCUITRY

Abstract

A system for converting an optical signal into an electrical signal includes at least one differential Trans-Impedance Amplifier (TIA). To minimize (preferably eliminate) DC offset issues at the TIA output, an Input Counter-Offset (ICO) circuit is provided to remove the DC component of the initial optical signal from the input to the TIA. To further maximize the removal of DC offset at the TIA output, an Output Counter-Offset circuit is provided to take DC offset from the TIA output for use as a negative feedback directly to the input of the TIA. Modifications of the present invention are also intended for use with two TIA terminations and with a travelling wave photodiode.

Claims20

Dependent claims

A system for converting an optical signal into an electrical signal which comprises:

a photodiode responsive to an optical signal for generating a photocurrent having an AC component Ipd(AC) and a DC component Ipd(DC);
an Input Counter-Offset (ICO) circuit for removing the DC component Ipd(DC) from the photocurrent to establish an ICO output including the AC component Ipd(AC);
a differential Trans-impedance Amplifier (TIA) having a first input port and a second input port, wherein the ICO output is received as an input to the first input port of the TIA;
and
an Output Counter-Offset (OCO) circuit for receiving a differential DC output from the TIA to detect any DC offset therein, wherein any DC offset in the TIA output is employed as a negative feedback to the second input port of the TIA to cancel the output DC offset.

2 more elements

A system for converting an optical signal into an electrical signal having an improved broader bandwidth which comprises:

a photodiode responsive to an optical signal for generating a photocurrent which splits into a first photocurrent having an AC component Ipd(AC) and a DC component Ipd(DC) and a second photocurrent having an AC component Ipd(AC) and a DC component Ipd(DC);
a first differential Trans-impedance Amplifier (TIA) having a first input port for receiving the first photocurrent from the photodiode, and having a second input port, a first output port and a second output port;
a second differential Trans-Impedance Amplifier (TIA) having a first input port for receiving the second photocurrent from the photodiode, and having a second input port, a first output port and a second output port;
a first Input Counter-Offset (ICO) circuit for removing the DC component Ipd(DC) from the first photocurrent to establish a first ICO output including its AC component Ipd(AC) wherein the first ICO output is received as an input to the first input port of the first differential TIA;
a second Input Counter-Offset (ICO) circuit for removing the DC component Ipd(DC) from the second photocurrent to establish a second ICO output including its AC component Ipd(AC) wherein the second ICO output is received as an input to the first input port of the second differential TIA;
and
a differential summer for receiving the output from the first DC-coupled output port of the first differential TIA and the output from the second DC-coupled output port of the first differential TIA, and for simultaneously receiving the output from the first DC-coupled output port of the second differential TIA and the output from the second DC-coupled output port of the second differential TIA to establish the electrical signal.

4 more elements

A system for converting a traveling wave photocurrent into an electrical signal which comprises:

a traveling wave photodiode responsive to an optical signal for generating a photocurrent which splits into a first photocurrent and a second photocurrent;
a first differential Trans-Impedance Amplifier (TIA) having a first input port for receiving the first photocurrent from the traveling wave photodiode, and having a second input port, a first DC output port and a second DC output port;
a second differential Trans-Impedance Amplifier (TIA) having a first input port for receiving the second photocurrent from the traveling wave photodiode, and having a second input port, a first DC output port and a second DC output port;
a first transmission line for transmitting the first photocurrent from the traveling wave diode to the first differential TIA;
and
a second transmission line for transmitting the second photocurrent from the traveling wave diode to the second differential TIA.

3 more elements

Dependencies are inferred from the claim text.

Differential trans-impedance amplifier receiver using counter-offset circuitry

Life of this patent

Differential trans-impedance amplifier receiver using counter-offset circuitry

Life of this patent

Abstract

Claims20