Segment DAC Conversion for Higher-Level Native DSD Audio
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Solution Overview
Problem
Existing DSD signal reproduction methods face challenges in maintaining high signal levels while preserving the native DSD format, particularly in non-native and native reproduction techniques, leading to suboptimal sound quality and limited dynamic range.
Innovation Solution
An audio D/A converter is designed with an N-bit segment type D/A converter, a shift register configured to store M-bits of DSD data, and a controller that generates an N-bit output code to increase signal level by controlling the number of 1s in the D/A converter, utilizing techniques like data weighted averaging to distribute 1s evenly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DSD signal is directly subjected to D/A conversion without converting into a PCM signal, then the DSD native reproduction is achieved, but the signal level is insufficient
Solution Approach 1:
The patent segments the 1-bit DSD signal into multiple bit positions (first bit position, second bit position, etc.) and processes each segment separately through different D/A converters. This segmentation allows the system to maintain DSD native reproduction while building up sufficient signal level by combining multiple segmented contributions.
Solution Approach 2:
The patent merges the output signals from multiple N-bit segment type D/A converters to produce the final output. By combining the segmented DSD signal portions with appropriate weighting, the system achieves both DSD native reproduction and adequate signal level through the cumulative effect of multiple converter outputs.
2Power
If the number of 1s in the output code is increased to raise signal level, then the signal level is improved, but the distribution of 1s becomes uneven causing distortion
Solution Approach 1:
The patent applies different weighting factors to different bit positions (first bit position, second bit position, etc.) based on their local characteristics in the DSD signal. This local quality approach allows each segment to contribute appropriately to the overall signal level while maintaining proper distribution through position-specific processing.
Solution Approach 2:
The patent changes the parameter of bit distribution by controlling the number of 1s in each N-bit output code differently for different bit positions. By adjusting the density and distribution of 1s in each segmented output according to its position, the system achieves both elevated signal level and uniform overall distribution when combined.
3Manufacturing precision
If a low-pass filter is applied to reproduce the original audio waveform from the DSD signal, then the audio waveform can be reproduced, but the dynamic range is limited
Solution Approach 1:
The patent introduces dynamic processing by varying the number of 1s in the output code based on the input DSD signal characteristics. This dynamic adjustment allows the system to adaptively optimize both waveform reproduction accuracy and dynamic range exploitation, moving beyond static low-pass filtering approaches.
Solution Approach 2:
The patent transitions from the traditional single-dimension low-pass filtering approach to a multi-dimensional approach by processing the DSD signal through multiple N-bit segment type D/A converters simultaneously. This dimensional expansion allows independent optimization of waveform reproduction and dynamic range in different processing dimensions before combining the results.
Data Source
AI summary
An audio D/A converter for converting direct stream digital (DSD) data having a modulation rate m into an analog signal includes: an N-bit (N≥2) segment type D/A converter, a shift register configured to store M-bits (N≤MSN/m) of the DSD data; and a controller configured to supply an N-bit output code containing p 1s to the segment type D/A converter when the number of 1s stored in the shift register is p.