Analog DC Offset Removal Circuit Without AC Signal Distortion

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Solution Overview

Problem

Conventional methods for removing DC offset from periodic analog signals often introduce undesirable signal distortions, such as phase shifts and delays, and require digitization or user input, which affect the AC component and are inefficient.

Innovation Solution

An analog signal processing system utilizing a first and second reference measurement circuit, a bias detection circuit, and a bias removal circuit to adaptively remove the DC component without affecting the AC component, using analog components only, without phase shift, delay, or digitization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional analog components (resistors and capacitors) are used to remove DC offset, then the DC component can be removed, but undesirable signal distortions are introduced in the output signal

Engineering Contradiction:

ImproveDC offset removal effectivenessVSAvoidsignal distortions

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces conventional passive analog components (resistors and capacitors) with an active operational amplifier-based circuit that uses feedback control. This substitution transforms the DC offset removal mechanism from a passive filtering approach to an active correction approach, eliminating signal distortions while effectively removing the DC component.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent employs a feedback mechanism where the output signal is fed back through a feedback network to the inverting input of the operational amplifier. This feedback control allows the circuit to automatically adjust and cancel the DC offset without introducing distortions, as the operational amplifier maintains the virtual ground condition at its inputs through continuous feedback adjustment.

Inventive Principle:

Principle #23Feedback

2Adaptability or versatility

If digital conversion is used to remove DC offset, then modifications can be performed on the signal, but the signal must be digitized which introduces complexity and potential loss of analog characteristics

Engineering Contradiction:

Improvesignal modification capabilityVSAvoiddigitization requirements

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces digital signal processing methods with an entirely analog operational amplifier-based circuit. This eliminates the need for analog-to-digital conversion, digital processing, and digital-to-analog conversion, thereby reducing device complexity while maintaining the ability to remove DC offset and preserve analog signal characteristics.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The operational amplifier circuit is self-regulating through its feedback mechanism, automatically detecting and correcting DC offset without requiring external control signals, user input, or complex processing. The circuit performs the DC offset removal function autonomously based on the virtual ground principle.

Inventive Principle:

Principle #25Self-service

3Reliability

If user input or external components (clocks, isolators) are required for DC offset removal, then the system can function, but the system complexity and ease of operation are reduced

Engineering Contradiction:

ImproveDC offset removal functionalityVSAvoiduser input requirements

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The operational amplifier circuit with feedback network is completely autonomous, requiring no user input, external clocks, or additional control components. The circuit automatically performs DC offset removal by maintaining the virtual ground condition through its inherent feedback mechanism, making it extremely easy to operate.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The operational amplifier-based DC offset removal circuit is universally applicable to various analog signals without requiring signal-specific configuration or external components. The same circuit topology works for different input signals, eliminating the need for signal-specific calibration or external control elements.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12526003B2Systems and methods for removing variable DC offset of periodic analog signals

Publication Date: 2026.01.13 BATTELLE SAVANNAH RIVER ALLIANCE LLC

AI summary

A signal processing system and method for removing a direct-current (DC) component from an analog input signal input is provided. The signal processing system includes an input transmission line, a first reference measurement circuit, a second reference measurement circuit, a bias detection circuit, and a bias removal circuit. The method includes determining, via the first reference measurement circuit, a first measured peak signal; determining, via the second reference measurement circuit, a second measured peak signal; determining, via the bias detection circuit, a bias signal indicative of the DC component of the analog input signal based at least in part on the first and second measured peak signals; and generating, via the bias removal circuit, an analog output signal based at least in part on the analog input signal and the bias signal. The analog output signal is the analog input signal with the DC component removed therefrom.