Ratiometric Position Sensing Circuit With Shared ADC Paths
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Solution Overview
Problem
Existing signal conditioning circuits for AC ratiometric position measurements in resolvers and LVDTs require additional circuitry and multiple ADCs, increasing costs and complexity, especially in applications like aircraft where multiple sensors need to be monitored simultaneously.
Innovation Solution
A signal conditioning circuit design that uses a shared multiplexer and filter structure for multiple sensors, along with a built-in test (BIT) signal and analog-to-digital converters (ADCs), to determine position measurements efficiently, reducing the number of ADCs required and minimizing gain errors through synchronous demodulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a multiplexer is used to sample signals successively from multiple sensors, then the number of ADCs is reduced, but gain errors and timing skew increase
Solution Approach 1:
A shared filter is introduced as an intermediary component between the multiplexer and the single ADC. This filter processes signals from multiple sensors sequentially, enabling the single ADC to accurately convert the filtered signals while minimizing gain errors and timing skew through the filter's signal conditioning capability
Solution Approach 2:
Multiple signal paths from different sensors are merged through a shared filter and multiplexer structure, allowing a single ADC to service multiple sensors. The shared filter ensures that signals are properly conditioned before being multiplexed and converted, maintaining measurement precision while reducing the number of ADCs required
2Measurement precision
If separate signal paths with individual ADCs are used for each sensor, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The shared filter is designed to handle signals from multiple sensors universally, performing the same filtering function for each sensor's signal path. This multi-functional component replaces multiple dedicated filter-ADC combinations, reducing device complexity while maintaining the precision benefits of individual signal processing
Solution Approach 2:
Multiple individual signal processing paths are merged into a shared filter structure that serves all sensors. This consolidation reduces the total number of components (filters and ADCs) while the filter's design ensures that each sensor's signal is properly conditioned, maintaining measurement precision with reduced complexity
3Measurement precision
If more ADCs are used for each sensor, then position measurement accuracy is improved, but cost increases
Solution Approach 1:
The shared filter acts as an intermediary that enables a single ADC to achieve the same measurement precision that would otherwise require multiple ADCs. By properly conditioning signals from multiple sensors before they reach the single ADC, the filter allows cost-effective manufacturing while maintaining high measurement accuracy
Solution Approach 2:
Instead of using multiple expensive ADCs, the design uses a single ADC that is 'copied' or shared across multiple sensor channels through the multiplexer. The shared filter ensures that each channel's signal is properly prepared, allowing the single ADC to accurately measure multiple sensors at different times without sacrificing precision, thereby reducing manufacturing cost
Data Source
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AI summary
Systems and methods for sensor position measurements are provided. Aspects include receiving, through a first signal path, a first secondary signal from a first sensor and a built in test (BIT) signal, wherein the first signal path comprises a first multiplexer (402-1, 402-2, 402-3, 402-4) connected to a first filter (404-1, 404-2, 404-3, 404-4), receiving, through a second signal path, a second secondary signal from the first sensor and the BIT signal, wherein the second signal path comprises a second multiplexer (406-1, 406-2) connected to a second filter, wherein the first signal path and the second signal path are connected to a third multiplexer, wherein the third multiplexer is connected to a first analog to digital converter (ADC), receiving, by a controller (410), an output signal from an output of the first ADC, and determining, by the controller, a position measurement for the first sensor based on the first secondary signal, the second secondary signal, and the BIT signal.