Semiconductor PWM Audio Circuit for Dual-Resonance Sound Output
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Solution Overview
Problem
Existing semiconductor devices and electronic apparatuses face challenges in reproducing high-quality sound, particularly in lower frequency bands, as they often rely on pseudo methods that do not actually output sound in these bands, limiting the quality of sound reproduction.
Innovation Solution
A semiconductor device with separate pulse width modulation (PWM) signal generation circuits for sound output units with different resonance frequencies, using PWM signals with varying pulse widths and periods to drive piezoelectric elements and diaphragms, allowing for the output of sounds across a wider frequency range, including human voice frequencies, by combining outputs from multiple units with distinct resonance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If pseudo sound data using harmonics is used to output sound in lower frequency band, then sound reproduction capability is improved, but actual sound output quality deteriorates because the sound is not actually output
Solution Approach 1:
The sound output system is divided into multiple independent sound output units, each responsible for specific frequency bands. The first sound output unit handles lower frequency bands while the second sound output unit handles higher frequency bands, allowing actual sound output across the full spectrum rather than relying on pseudo harmonics
Solution Approach 2:
The patent introduces a frequency dimension differentiation by using sound output units with different resonance frequencies. This allows the system to output actual sounds across multiple frequency bands simultaneously, transforming the one-dimensional pseudo-harmonic approach into a multi-dimensional actual sound output approach
2Adaptability or versatility
If multiple sound output units with different resonance frequencies are used, then frequency band coverage is improved, but device complexity increases
Solution Approach 1:
Each sound output unit is designed with multi-functionality, where the same basic structure (piezoelectric element + diaphragm) can operate at different resonance frequencies. The PWM signal generation circuits can generate appropriate drive signals for different frequency bands using the same circuit architecture, reducing overall system complexity
Solution Approach 2:
The system achieves different frequency responses by changing operational parameters (resonance frequency, PWM pulse width, PWM period) rather than using fundamentally different circuit architectures. This allows multiple frequency bands to be covered while maintaining circuit simplicity through parameter variation
3Manufacturing precision
If PWM signals with varying pulse widths and periods are generated for different sound output units, then sound quality is improved, but circuit complexity increases
Solution Approach 1:
The PWM signal generation circuits dynamically adjust pulse width and period based on the required frequency band and sound data. The first PWM signal generation circuit varies pulse width for lower frequency bands while the second PWM signal generation circuit varies both pulse width and period for higher frequency bands, achieving high sound quality through dynamic parameter adjustment
Solution Approach 2:
Different PWM signal characteristics are generated locally for different sound output units according to their specific resonance frequencies. Each unit receives customized PWM signals optimized for its frequency range, with the first unit receiving signals with longer periods and the second unit receiving signals with shorter periods, improving overall sound quality
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
The solution enables high-quality sound reproduction across a broader frequency band, effectively reproducing human voice and other sounds with reduced noise and harmonic distortion, while minimizing circuit scale and power consumption.
Implementation Method 1
a first piezoelectric element and a first diaphragm to output a sound
Implementation Method 2
a first diaphragm to output a sound
Implementation Method 3
a first sound output unit including a first piezoelectric element and a first diaphragm to output a sound
Data Source
AI summary
A semiconductor device includes a sound data reading circuit that reads sound data from a memory, a first pulse width modulation signal generation circuit that generates a first pulse width modulation signal whose pulse width changes based on the sound data, and a second pulse width modulation signal generation circuit that generates a second pulse width modulation signal whose pulse width changes based on the sound data, wherein the first pulse width modulation signal is a signal for a first sound output unit including a first piezoelectric element and a first diaphragm to output a sound, and the second pulse width modulation signal is a signal for a second sound output unit including a second piezoelectric element and a second diaphragm and having a higher resonance frequency than the first sound output unit to output a sound.