Ratiometric Position Measurement Using BIT-Assisted Shared ADCs
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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 cost and complexity, especially in applications like aircraft where sampling speed and component cost need to be balanced.
Innovation Solution
A signal conditioning circuit with a shared multiplexing and filtering architecture that uses a built-in test signal and excitation signal to determine position measurements, reducing the number of ADCs required by canceling gain errors through synchronous demodulation, and allowing wider multiplexers for faster acquisition and lower cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate signal paths with individual ADCs are used for each sensor signal, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges multiple signal paths into a shared architecture where a single ADC services multiple sensor signals through time-division multiplexing. The MUX selectively connects different sensor outputs to the shared ADC at different time intervals, allowing one ADC to process signals from multiple sensors without requiring separate ADCs for each sensor, thereby reducing device complexity and cost while maintaining measurement capability.
Solution Approach 2:
The shared ADC is designed to perform multiple functions by processing signals from different sensors at different time intervals. The MUX enables the ADC to be universally applied to various sensor inputs (E1, E2, BIT1, BIT2) sequentially, making the ADC a multi-functional component that serves the entire sensor array rather than being dedicated to a single sensor channel.
2Productivity
If multiple ADCs are used for simultaneous signal conversion, then sampling speed is improved, but cost increases
Solution Approach 1:
The system employs periodic action through time-division multiplexing where the MUX rapidly switches between different sensor signals in a periodic sequence. The ADC converts signals from multiple sensors by cycling through each input in rapid succession, creating an effective sampling system that achieves high overall acquisition rates without requiring multiple simultaneous ADCs. The periodic switching enables one ADC to service multiple sensors at high speed.
3Ease of manufacture
If component count is reduced to lower cost, then ease of manufacture is improved, but reliability may worsen
Solution Approach 1:
The MUX acts as an intermediary component that manages the shared resource (single ADC) among multiple sensors. By introducing the MUX as a mediator, the system achieves cost reduction through component sharing while maintaining reliability through controlled signal routing. The MUX ensures that each sensor signal receives dedicated conversion time slots, preventing signal interference and maintaining measurement integrity despite the reduced component count.
Data Source
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 connected to a first filter, 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 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, 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.