Asymmetrical PWM D/A Conversion for Wider Dynamic Range
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Solution Overview
Problem
Conventional D/A conversion devices face limitations in increasing dynamic range without increasing the operation clock frequency, leading to high power consumption, especially in electronic musical instruments.
Innovation Solution
Implementing asymmetrical pulse width modulation (PWM) signals with a D/A conversion device that includes a second quantizer to generate correction values, allowing for increased quantization stages without raising the operation clock frequency, thereby expanding the dynamic range and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the operation clock frequency is increased to increase the dynamic range, then the dynamic range is improved, but the power consumption increases
Solution Approach 1:
The patent applies asymmetry by using asymmetrical pulse width modulation instead of conventional symmetrical PWM. The pulse signals are designed with asymmetric duty ratios where the high-level period and low-level period are not equal, allowing for increased quantization stages and dynamic range without requiring higher clock frequencies. This asymmetrical approach enables the system to achieve 16-bit dynamic range at lower operating frequencies, thereby reducing power consumption while maintaining measurement precision.
2Measurement precision
If the operation clock frequency is increased to increase the number of quantization stages, then the quantization accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent employs asymmetrical PWM waveforms with different high-level and low-level periods to increase the number of quantization stages. By dividing the asymmetrical period into multiple phases and using phase control, the system achieves higher quantization accuracy (16-bit) without requiring proportionally higher clock frequencies or more complex circuitry. The asymmetrical structure allows efficient use of each clock cycle, reducing the overall device complexity compared to symmetrical approaches.
Solution Approach 2:
The patent utilizes periodic action through multi-phase control within each asymmetrical PWM period. The pulse width modulation is divided into multiple phases (first phase, second phase, etc.) that occur periodically, allowing the system to achieve fine quantization resolution through phase-based control rather than requiring extremely high frequency operation. This periodic multi-phase approach enables high quantization accuracy while maintaining manageable device complexity.
Data Source
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AI summary
A digital-to-analog conversion device which performs integration processing for integrating a difference between an input signal and a first return signal generated based on the input signal, and outputting an integration result, first quantization processing for quantizing the integration result, and outputting a first quantization signal, first return signal output processing for outputting the first return signal by adding to the first quantization signal a correction value delay signal acquired by a correction value signal outputted based on the integration result being delayed, and output processing for outputting output signals including a signal whose pulse width is asymmetrical to center of a processing period, based on the first quantization signal, in which the correction value signal includes a signal indicating a correction value for correcting a difference between a center of the pulse width asymmetrical to the center of the processing period and the center of the processing period.