Op-Amp Signal Combining Circuit for Wide Dynamic Range Input
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Solution Overview
Problem
Conventional amplifying circuits using operational amplifiers struggle to accurately amplify input signals beyond 120 dB SPL without distortion, as they either saturate or fail to maintain accuracy for both normal and high-level inputs when operational amplifiers are arranged in parallel or series.
Innovation Solution
An amplifying circuit with an operational amplifier having a negative feedback path and a signal combining unit that adds a weighted feedback signal to the output, allowing for efficient generation of both normal and excessive level outputs by adjusting coefficients K1 and K2 to match the input signal's waveform.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If operational amplifiers are arranged in parallel to distribute signals, then the circuit can handle both normal and large input levels, but the output signal from the normal level operational amplifier cannot ensure sufficient accuracy
Solution Approach 1:
The patent combines the output signal from the operational amplifier with a scaled version of the input signal through a signal combining unit. This merging allows the circuit to maintain accuracy for both normal and large input levels by adding the unsaturated input signal component to compensate for distortion in the amplified output.
2Power
If operational amplifiers are arranged in series to amplify large input signals, then the output relative to large input can be obtained, but sufficient accuracy cannot be maintained for the normal level output
Solution Approach 1:
The patent applies partial action by using only a portion of the input signal (through the coefficient K1) to compensate for the amplified output. This allows the circuit to handle large input signals while maintaining accuracy by adding a scaled version of the original input signal that has not been saturated by amplification.
3Device complexity
If a single operational amplifier is used with voltage input type, then the circuit is simple, but it cannot amplify input signals with amplitude exceeding the power source voltage
Solution Approach 1:
The patent makes the single operational amplifier circuit universal by combining its output with a scaled input signal. This multi-functional approach allows the same simple circuit structure to handle both normal and excessive input signal amplitudes, effectively extending the input range beyond what a single operational amplifier could handle alone.
4Adaptability or versatility
If two operational amplifiers are provided for normal and large levels, then both normal and large input signals can be processed, but the device complexity increases
Solution Approach 1:
The patent makes a single operational amplifier perform multiple functions by combining its amplified output with a scaled version of the input signal. This single operational amplifier circuit effectively handles both normal and large input levels, replacing the need for two separate operational amplifiers while maintaining the ability to process different input levels.
Data Source
AI summary
To efficiently obtain two outputs including one at a normal level and the other at an excessive level. An input signal input to the negative input terminal of an operational amplifier (14) having a negative feedback path is amplified to output an output signal. Signal combining units (18, 20, 22) are provided for adding in a weighted manner a negative input terminal side signal obtained by combining the input signal input to the negative input terminal of the operational amplifier (14) and a feedback signal from the negative feedback path and the output signal from the operational amplifier to output a combined signal, so that two signals, namely the output signal from the operational amplifier (14) and the combined signal, are obtained.