Delta-Sigma ADC Output Compression for Lower Bus Power
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Solution Overview
Problem
Digital audio systems face challenges in efficiently communicating digital signals with numerous quantization levels over serial digital buses, leading to decreased communication throughput and increased power consumption due to frequent bit changes.
Innovation Solution
A system incorporating a delta-sigma analog-to-digital converter and a digital compression circuit that compresses the digital output signal into fewer quantization levels, using a loop filter and feedback mechanism to reduce bit transitions and minimize power consumption, while maintaining signal quality through lossless compression or minimizing degradation outside human hearing ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If numerous quantization levels are used to represent audio signal with sufficient quality, then audio signal quality is improved, but communication throughput decreases and power consumption increases
Solution Approach 1:
The patent segments the digital signal transmission into two parts: an uncompressed digital output signal from the delta-sigma ADC and a separate compression control signal. The compression circuit uses the control signal to dynamically adjust compression parameters, allowing the system to maintain high audio quality when needed while reducing bit depth and communication overhead when possible, thus resolving the throughput-quality tradeoff
Solution Approach 2:
The patent implements dynamic compression where the compression ratio and parameters are adjusted in real-time based on the characteristics of the audio signal. The compression circuit dynamically changes the number of quantization levels used for transmission, using full precision when signal quality is critical and reducing precision when throughput is prioritized, thereby adaptively resolving the contradiction between quality and communication efficiency
2Measurement precision
If numerous quantization levels are used to represent audio signal with sufficient quality, then audio signal quality is improved, but power consumption increases
Solution Approach 1:
The patent applies partial compression by selectively compressing only certain portions of the audio signal or using variable compression ratios. Instead of uniformly compressing all data, the system applies compression adaptively based on signal characteristics, maintaining high quality where necessary while reducing power consumption through selective bit-depth reduction in less critical signal portions
Solution Approach 2:
The patent changes the quantization parameter (number of bits per sample) dynamically based on signal requirements. The compression circuit adjusts the effective bit depth by changing compression parameters in real-time, using higher precision when audio quality is paramount and lower precision when power conservation is prioritized, thus resolving the energy-quality tradeoff
3Measurement precision
If digital codes with many bits are transmitted over serial digital bus, then audio signal quality is maintained, but communication throughput decreases
Solution Approach 1:
The patent embeds compression control information within the existing digital audio data stream structure. The compression circuit processes the high-precision digital signal and generates compressed output that maintains the essential audio information while reducing the effective data width, allowing nested transmission of both quality-preserving and throughput-optimizing elements within the same communication framework
Data Source
AI summary
A system may include a delta-sigma analog-to-digital converter and a digital compression circuit. The delta-sigma analog-to-digital converter may include a loop filter having a loop filter input configured to receive an input signal and generate an intermediate signal responsive to the input signal, a multi-bit quantizer configured to quantize the intermediate signal into an uncompressed digital output signal, and a feedback digital-to-analog converter having a feedback output configured to generate a feedback output signal responsive to the uncompressed digital output signal in order to combine the input signal and the feedback output signal at the loop filter input. The digital compression circuit may be configured to receive the uncompressed digital output signal and compress the uncompressed digital output signal into a compressed digital output signal having fewer quantization levels than that of the uncompressed digital output signal.