Op-Amp Clipping Detection Using Input Terminal Potential Difference

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing amplifiers prematurely attenuate input signals to prevent clipping, leading to early reduction in sound volume and excessive distortion, as they rely solely on output potential detection rather than quantitatively assessing excessive input levels.

Innovation Solution

An amplifier design incorporating a variable gain unit, a negative feedback amplifying unit with an operational amplifier, and a controller that compares the potential difference between the positive and negative phase input terminals to detect clipping, allowing controlled attenuation and maintaining sound volume by permitting clipping up to a preset level.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the input signal is attenuated immediately upon detecting output potential exceeding predetermined value, then clipping prevention is improved, but sound volume feeling deteriorates due to premature attenuation

Engineering Contradiction:

Improveclipping preventionVSAvoidsound volume feeling

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the detection parameter from output potential alone to potential difference between positive and negative input terminals of the operational amplifier. This parameter change allows for more accurate assessment of excessive input conditions, enabling attenuation only when truly necessary, thus preventing premature attenuation while maintaining sound volume feeling.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the simple output potential detection mechanism with a comparator-based system that measures potential difference at the operational amplifier's input terminals. This substitution enables quantitative assessment of excessive input levels, allowing controlled attenuation that preserves sound quality while preventing clipping.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If output potential detection alone is used to detect clipping, then detection simplicity is improved, but detection accuracy deteriorates leading to unreliable clipping determination

Engineering Contradiction:

Improvedetection mechanismVSAvoidclipping detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent substitutes simple output potential detection with a comparator circuit that measures the potential difference between the positive and negative input terminals of the operational amplifier. This substitution provides reliable clipping detection by directly monitoring the conditions at the amplifier's input stage, where clipping actually begins to occur.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a comparator as an intermediary device between the operational amplifier and the attenuation control system. The comparator quantitatively assesses the potential difference and provides accurate clipping detection, serving as a mediator that translates physical electrical conditions into reliable control signals.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS7551031B2Amplifier

Publication Date: 2009.06.23 YAMAHA CORP

AI summary

The amplifier comprises an inverting negative feedback amplifier circuit using an operational amplifier, a comparator for comparing the potential of the negative phase input terminal of the operational amplifier with the reference potential Vref of the comparator, and a low-pass filter. The imaginary short state of the operational amplifier is lost when clipping occurs on the output signal. It is thus possible to detect clipping by monitoring the potential of the negative phase input terminal.