Dynamic Element Rotation for Faster, More Accurate Incremental ADCs
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Solution Overview
Problem
Second order and higher incremental analog-to-digital converters (ADCs) face increased residual variation due to non-equal sample weights, which slows down conversion times and reduces accuracy compared to first order systems.
Innovation Solution
Implementing a second order dynamic element rotation scheme where signal generating elements are switched through configurations in a first sequence and then reversed, allowing non-constant weights to be allocated based on a noise shaping function for effective averaging of sample signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If second order and higher incremental ADCs use non-constant weights for sample integration, then conversion speed is improved, but residual variation increases and accuracy deteriorates
Solution Approach 1:
The patent applies dynamic element matching by continuously rotating and reconfiguring the signal generating elements through multiple configurations during the integration process. This dynamic reconfiguration ensures that each physical element contributes to multiple samples with different weights, thereby averaging out the residual variation caused by non-constant weights and maintaining high conversion speed while improving accuracy
Solution Approach 2:
The patent changes the weighting parameters dynamically by using different configurations of signal generating elements for different samples. By varying which elements are active in each configuration and how they are weighted, the system achieves non-constant weights that speed up conversion while the overall averaging process maintains accuracy by compensating for residual variation
2Measurement precision
If dynamic element matching is used to reduce mismatch effects, then device ratio accuracy is improved, but system complexity increases
Solution Approach 1:
The patent segments the signal generating function across multiple identical elements that can be independently configured. By dividing the overall signal generation task among multiple elements that are rotated through different configurations, the system achieves high device ratio accuracy through averaging while keeping each individual element simple and the overall structure modular
Solution Approach 2:
The patent implements periodic rotation through a fixed sequence of configurations, where each element cycles through predetermined positions in a repeating pattern. This periodic action simplifies the control logic compared to arbitrary reconfiguration, as the system only needs to implement a fixed rotation sequence that naturally achieves the desired averaging effect over time
3Measurement precision
If first order incremental ADC is used with constant weights, then accuracy is maintained, but conversion time increases
Solution Approach 1:
The patent changes from constant weights to non-constant weights in second order and higher incremental ADCs, which accelerates the convergence of the integration process. This parameter change in the weighting function allows the system to achieve the same accuracy level in fewer integration steps, thereby reducing conversion time while maintaining measurement precision
Data Source
AI summary
A sensor system for generating sample analog signals for processing by a signal processing circuit that utilizes non-constant weights includes a plurality of signal generating elements and a switching network having a plurality of switches operably coupled to the plurality of signal generating elements. The switching network is configured to switch the plurality of signal generating elements between a plurality of different configurations. The system includes a dynamic element matching (DEM) control system for controlling the switch network to implement a second order DEM rotation scheme in which the plurality of signal generating elements are switched to each configuration in the plurality of configurations in a first sequence and then switched to each configuration in the plurality in a second sequence, the second sequence being the reverse of the first sequence.