DTIA Offset Compensation via Regulated Inverter Supply

Solution Overview

Problem

Differential transimpedance amplifiers (DTIAs) face challenges in maintaining symmetric differential output signals due to direct current (DC) offset, with existing compensation techniques often reducing the amplifier's bandwidth or gain.

Innovation Solution

A DC offset compensation circuit using a series of inverters and a digital-to-analog converter (DAC) controlled voltage regulator adjusts the supply voltage to specific inverters, reducing DC offset while maintaining the amplifier's bandwidth or gain.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If DC offset compensation techniques are applied to DTIAs, then the output signal symmetry is improved, but the bandwidth or gain is reduced

Engineering Contradiction:

Improveoutput signal symmetryVSAvoidbandwidth

Core Design Contradiction:

Stability of the object's compositionVSSpeed

Solution Approach 1:

The DTIA is divided into two separate voltage-regulated inverter chains, each receiving independent supply voltages from different voltage regulators. This segmentation allows independent control of each chain's operating point, enabling DC offset compensation without affecting the overall bandwidth through invasive tapping.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The supply voltages to the inverters are dynamically adjusted by voltage regulators to compensate for DC offset. By changing the voltage parameters of specific inverter chains based on detected output asymmetry, the system corrects DC offset while maintaining the bandwidth characteristics of the amplifier.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If DC offset compensation techniques are applied to DTIAs, then the output signal symmetry is improved, but the gain is reduced

Engineering Contradiction:

Improveoutput signal symmetryVSAvoidgain

Core Design Contradiction:

Stability of the object's compositionVSPower

Solution Approach 1:

The DTIA is divided into two separate voltage-regulated inverter chains, each receiving independent supply voltages from different voltage regulators. This segmentation allows independent control of each chain's operating point, enabling DC offset compensation without affecting the overall gain through invasive tapping.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The supply voltages to the inverters are dynamically adjusted by voltage regulators to compensate for DC offset. By changing the voltage parameters of specific inverter chains based on detected output asymmetry, the system corrects DC offset while maintaining the gain characteristics of the amplifier.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS12068723B2Direct current offset compensation circuit

Publication Date: 2024.08.20 CISCO TECHNOLOGY INC

AI summary

A differential transimpedance amplifier (DTIA) includes a first input, a second input, a first output, and a second output. The DTIA also includes a first inverter and a second inverter connected in series to the first input. The DTIA further includes a third inverter and a fourth inverter connected in series to the second input. The first inverter and the fourth inverter receive a first supply voltage from a first voltage regulator. The second inverter and the third inverter receive a second supply voltage from a second voltage regulator. The first supply voltage changes (i) based on a difference between voltages on the first output and the second output and (ii) while the second supply voltage remains fixed.