Speaker Amplifier Circuit for Impedance Peak Detection
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Solution Overview
Problem
Existing semiconductor devices for speaker failure detection require a dedicated physical quantity measuring device to apply an alternating-current voltage, resulting in a large circuit for impedance measurement, which is inefficient.
Innovation Solution
A semiconductor device with a modulation circuit, amplifier circuits, and a peak frequency detection circuit that modulates signals to detect the frequency range where the impedance of a sound reproduction device peaks, allowing for impedance measurement without the need for a dedicated measuring device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated physical quantity measuring device is used to apply alternating-current voltage for impedance measurement, then measurement precision is improved, but device complexity increases and circuit size becomes large
Solution Approach 1:
The amplifier circuits that normally function to drive the speaker are made to serve dual purposes: they both amplify audio signals for sound reproduction and apply test signals for impedance measurement. By switching between normal operation mode and inspection mode, the same hardware resources are utilized for both audio output and diagnostic functions, eliminating the need for separate dedicated measuring devices.
Solution Approach 2:
The system performs self-diagnosis by using its own amplifier circuits to generate test signals and measure impedance. The amplifier circuits apply the test signal to the speaker and simultaneously measure the resulting current, allowing the system to self-test without requiring external specialized equipment.
2Measurement precision
If a dedicated physical quantity measuring device is used to measure current for impedance calculation, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The amplifier circuits are designed to perform both audio signal amplification and current measurement functions. During inspection mode, the same amplifier circuits that drive the speaker also measure the current flowing through it, allowing impedance calculation without separate measuring instruments.
Solution Approach 2:
The patent combines the test signal generation, signal amplification, and current measurement functions into a single integrated system. The amplifier circuits simultaneously handle signal output and measurement, merging multiple functions into unified hardware components.
3Measurement precision
If the amplifier circuits operate in inspection mode with high impedance outputs, then impedance measurement accuracy is improved, but sound reproduction capability is temporarily reduced
Solution Approach 1:
The system alternates between normal operation mode for sound reproduction and inspection mode for impedance measurement. By periodically switching between these modes, the system achieves both high-fidelity audio output and accurate diagnostic measurement at different time intervals.
Solution Approach 2:
The amplifier circuits dynamically switch their operating characteristics between normal mode (low output impedance for power delivery) and inspection mode (high output impedance for measurement accuracy). This dynamic adaptation allows the system to optimize performance for the current operational context.
Data Source
AI summary
Provided is a semiconductor device. In a first operation mode, a first modulated signal is input to a plurality of inverter circuits provided in a first amplifier circuit, and a second modulated signal is input to a plurality of inverter circuits provided in a second amplifier circuit. In a second operation mode, a test signal generation circuit modulates a test signal to generate a third modulated signal and a fourth modulated signal. The third modulated signal is input to some of the plurality of inverter circuits provided in the first amplifier circuit, and outputs of other inverter circuits have high impedances. The fourth modulated signal is input to some of the plurality of inverter circuits provided in the second amplifier circuit, and outputs of other inverter circuits have high impedances. A peak frequency detection circuit detects a frequency range including a frequency of the test signal at which an impedance of a sound reproduction device peaks.