Differential Detection Circuit With In-Phase Feedback for Wider Output Range
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Solution Overview
Problem
Existing physical quantity detection devices face a trade-off between sensitivity and output range, making it difficult to achieve high accuracy in detecting physical quantities due to the single-ended Q/V conversion circuit's sensitivity to all inputs, including unnecessary signals from resonance.
Innovation Solution
A circuit device with a physical quantity detection signal outputting circuit that includes first and second amplifiers and a differential amplifier circuit, along with an in-phase feedback circuit to detect and output a differential amplified signal, improving detection accuracy by separating and attenuating in-phase signal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the gain of the Q/V conversion circuit is increased to improve detection accuracy, then sensitivity is improved, but the output range is reduced causing signal saturation
Solution Approach 1:
The patent segments the signal processing into two independent paths: a differential amplifier path for useful signals and a separate in-phase feedback path for resonance signals. This allows the Q/V conversion circuit to operate at high gain for sensitivity while the feedback path independently handles the output range issue by attenuating resonance components.
Solution Approach 2:
The patent introduces an in-phase feedback circuit that detects resonance signals and feeds back attenuation control to the differential amplifier. This feedback mechanism dynamically adjusts the amplification level based on detected resonance, allowing high sensitivity operation while preventing output saturation through adaptive gain control.
2Adaptability or versatility
If the sensitivity of the Q/V conversion circuit is reduced to secure output range, then the output range is improved, but detection accuracy deteriorates
Solution Approach 1:
The patent extracts and separates the resonance signal component from the useful differential signal through the in-phase feedback circuit. By taking out the resonance component and processing it independently, the system can maintain high sensitivity for the useful signal while the extracted resonance component is handled separately through feedback attenuation.
Solution Approach 2:
The in-phase feedback circuit acts as an intermediary between the Q/V conversion circuit and the final output. It mediates the interaction between sensitivity and output range by detecting resonance signals and providing feedback control, allowing the main signal path to operate at optimal sensitivity without being constrained by output range limitations.
3Device complexity
If a single-ended Q/V conversion circuit is used to simplify the circuit structure, then device complexity is reduced, but the circuit becomes sensitive to all inputs including unnecessary resonance signals
Solution Approach 1:
The patent uses feedback to address the unwanted sensitivity to resonance signals. The in-phase feedback circuit continuously monitors the output for resonance components and adjusts the differential amplifier gain accordingly, allowing the simple single-ended Q/V conversion circuit to maintain its structural simplicity while dynamically compensating for harmful sensitivity through feedback control.
Data Source
AI summary
A circuit device includes a physical quantity detection signal outputting circuit including a first amplifier that receives a first signal output from a physical quantity detection element detecting a physical quantity and outputs a first amplified signal obtained by amplifying the first signal, a second amplifier that receives a second signal output from the physical quantity detection element and outputs a second amplified signal obtained by amplifying the second signal, and a differential amplifier circuit that outputs a differential amplified signal obtained by amplifying a difference between the first amplified signal and the second amplified signal, the physical quantity detection signal outputting circuit outputting a physical quantity detection signal corresponding to the physical quantity based on the differential amplified signal, and an in-phase feedback circuit that detects an in-phase signal component included in the first amplified signal and the second amplified signal, and outputs a feedback signal based on a detection signal of the in-phase signal component to the first amplifier and the second amplifier.