On-Demand DAC Segmentation in Microphone Sigma-Delta ADCs
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Digital microphones face challenges with quantization and thermal noise in analog-to-digital converters (ADCs), where increasing resolution does not diminish thermal noise, and existing solutions fail to efficiently manage noise and power consumption effectively.
Innovation Solution
A sigma-delta ADC with an on-demand Digital-to-Analog Converter (DAC) that includes at least one always-on DAC element and a plurality of on-demand DAC elements, which are progressively enabled based on the magnitude of the analog input signal, allowing for dynamic power management and noise reduction by disabling or placing buffers in low power mode to prevent thermal noise from affecting the output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution of the ADC is increased to reduce quantization noise, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The DAC is segmented into multiple individual DAC elements that can be independently controlled. Instead of using a single high-resolution DAC, the patent divides the DAC into multiple lower-resolution elements that are selectively activated based on the input signal magnitude, thereby reducing overall device complexity while maintaining measurement precision.
Solution Approach 2:
The patent implements dynamic control of DAC elements by progressively enabling or disabling individual DAC elements based on the magnitude of the analog input signal. This dynamic adaptation allows the system to use only the necessary number of DAC elements for each signal level, reducing complexity for low signals while maintaining precision for high signals.
2Reliability
If all DAC elements are always on to maintain ADC stability, then reliability is improved, but power consumption and thermal noise increase
Solution Approach 1:
The patent dynamically adjusts the operational state of DAC elements based on signal conditions. During low-power modes or when processing low-magnitude signals, fewer DAC elements are activated, reducing power consumption. The always-on DAC elements are strategically positioned to maintain ADC stability while minimizing their number.
Solution Approach 2:
Different DAC elements have different operational characteristics - some are always-on to maintain stability, while others are on-demand to reduce power consumption. This local differentiation in quality and function allows the system to optimize both reliability and power efficiency simultaneously.
3Measurement precision
If more DAC elements are enabled to handle higher signal magnitudes, then measurement precision is improved, but thermal noise increases
Solution Approach 1:
The patent implements progressive enabling of DAC elements based on the magnitude of the analog input signal. For low-magnitude signals, only a subset of DAC elements is activated, minimizing thermal noise. As signal magnitude increases, additional DAC elements are progressively enabled to maintain measurement precision without unnecessarily activating all elements that would generate excess thermal noise.
Data Source
AI summary
An analog-to-digital converter (ADC) includes a loop filter having an input for receiving an analog input signal; a quantizer having an input coupled to an output of the loop filter, and an output for providing a digital output signal; and a digital-to-analog converter (DAC) having an input coupled to an output of the quantizer, and an output coupled to the loop filter, wherein the DAC includes at least one always-on DAC element, and a plurality of on-demand DAC elements.