Differential Amplifier Feedforward Bias Correction for Small-Signal Accuracy

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing differential amplifiers suffer from low accuracy due to an unacceptably large offset in common-mode voltage output caused by small input signals.

Innovation Solution

A novel differential amplifier with a feedforward bias correction circuit that dynamically adjusts the common-mode voltage output based on the input voltage, using a bias correction circuit that includes a clamping voltage setting circuit and a common-mode voltage regulation circuit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a differential amplifier is used for direct-current amplification with small input signals, then the amplifier can provide balanced input and output with small zero drift, but the common-mode voltage output produces an unacceptably large offset leading to low accuracy

Engineering Contradiction:

Improveaccuracy of differential amplifierVSAvoidcommon-mode voltage offset

Core Design Contradiction:

Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The patent implements a feedback mechanism where the common-mode voltage output is fed back to a correction circuit that generates a compensation signal. This feedback loop continuously monitors the common-mode voltage and adjusts the bias voltage to counteract the offset, thereby improving measurement precision without sacrificing the amplifier's inherent low zero drift characteristics

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically adjusts the bias voltage parameter based on the common-mode voltage level. By changing the bias voltage in response to common-mode variations, the system optimizes the operating point of the differential amplifier to minimize offset errors while maintaining accurate small signal amplification

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the bias voltage is adjusted to reduce common-mode voltage offset, then accuracy improves, but the circuit complexity increases due to additional correction circuits

Engineering Contradiction:

Improveaccuracy of differential amplifierVSAvoidcircuit structure of differential amplifier

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the bias correction functionality with the existing differential amplifier structure by integrating the correction circuit into the same operational framework. The correction circuit shares common nodes and power supplies with the main amplifier, allowing offset compensation without requiring completely separate circuitry, thus limiting the increase in device complexity

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20250202437A1Novel differential amplifier with feedforward bias correction circuit, and device

Publication Date: 2025.06.19 OMNIVISION INTEGRATED CIRCUITS GROUP INC

AI summary

A novel differential amplifier with a feedforward bias correction circuit, and a device. Common-mode voltage output of a differential amplifier is dynamically adjusted based on an input voltage by using a bias correction circuit. This can greatly reduce an input voltage error of the differential amplifier caused by an offset of the common-mode voltage output, so that a quite small input signal can be detected at high precision, assisting a common-mode regulation channel in tracking the common-mode voltage output, thereby reducing the offset of the common-mode voltage output and improving accuracy of the differential amplifier.