Operational Amplifier Offset Cancellation via Alternating Units

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Solution Overview

Problem

Existing operational amplifiers struggle to continuously generate output signals while canceling offset voltages, as previous methods result in non-continuous output signals due to alternating holding and feedback operations.

Innovation Solution

The operational amplifier employs two identical operational amplification units that alternately perform canceling and non-canceling operations, using capacitors to accumulate and cancel offset voltages, with an output selection circuit ensuring continuous output generation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the area of elements configuring the operational amplifier is increased to cancel offset voltage, then the output error is reduced, but the device area and cost increase

Engineering Contradiction:

Improveoutput errorVSAvoiddevice area

Core Design Contradiction:

Measurement precisionVSArea of stationary object

Solution Approach 1:

The operational amplifier is divided into two identical operational amplification units that operate alternately. Each unit has its own capacitor for offset accumulation. This segmentation allows offset cancellation without requiring large element areas in a single continuous operation mode.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The two operational amplification units alternately perform canceling operations and non-canceling operations in periodic cycles. During each cycle, one unit accumulates offset voltage while the other provides continuous output. This periodic alternation enables offset cancellation without interrupting the overall output signal continuity.

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If holding or accumulating offset voltage is performed to cancel offset, then offset cancellation is achieved, but the output signal becomes non-continuous

Engineering Contradiction:

Improveoffset cancellationVSAvoidoutput signal continuity

Core Design Contradiction:

Measurement precisionVSDuration of action of stationary object

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

While one operational amplification unit performs offset accumulation and cancellation, the other unit continues to amplify the input signal and provide output. This ensures the output signal remains continuous without interruption, solving the problem of non-continuous output in prior art methods.

Inventive Principle:

Principle #20Continuity of useful action

3Duration of action of stationary object

If two operational amplification units are used to alternate between canceling and non-canceling operations, then continuous output is maintained, but the device complexity increases

Engineering Contradiction:

Improveoutput signal continuityVSAvoidcircuit complexity

Core Design Contradiction:

Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent uses two identical operational amplification units with the same circuit configuration. Each unit includes operational amplifiers, capacitors, and switching elements arranged in replicate structures. This copying approach simplifies design and analysis while enabling continuous output through alternating operation.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The two operational amplification units share common input terminals and output terminals, and their control signals are coordinated through a switching mechanism. This merging of input/output interfaces and coordinated control reduces overall system complexity compared to having completely separate systems.

Inventive Principle:

Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach allows for continuous output signal generation without increasing the operational amplifier's area, reducing costs by minimizing the need for larger elements and maintaining accurate gain settings.

Implementation Method 1

a first capacitor C1a. A first operational amplification unit 11a connected to the first capacitor C1a has a first offset voltage

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

an operational amplifier for generating an output voltage by amplifying an input voltage

Methodology Applied

Scientific EffectElectrical amplification:

Data Source

PatentUS7342443B2Operational amplifier

Publication Date: 2008.03.11 MONTEREY RESEARCH LLC

AI summary

An operational amplifier for canceling an offset and continuously generating an output signal. The operational amplifier includes a first operational amplification unit and a second operational amplification unit each having at least one electrical characteristic that is substantially the same as one another. One of the operational amplification units performs a canceling operation (holding operation and compensation operation) of the offset voltage while the other operational amplification unit performs a non-canceling operation and generates the output voltage by amplifying an input voltage. Both operational amplification units alternately perform the canceling operation and the non-canceling operation.