Full Bridge Sensor Reference Voltage Noise Tracking
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Solution Overview
Problem
Existing sensor systems with resistive sensing elements in full bridge configurations face challenges in generating accurate and low-noise reference voltage levels, leading to deteriorated performance due to high frequency noise conversion and increased power consumption, especially when dealing with intense noise on the supply voltage.
Innovation Solution
A sensor system design that includes two sensor paths and a processing unit, where the reference signals derived from the second sensor path track voltage ripples in the supply voltage, allowing the output signal to be independent of supply voltage fluctuations, thereby improving accuracy and reducing noise impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If reference voltage levels are derived indirectly from supply voltage by means of voltage dividers, then the circuit implementation is simple, but the accuracy and noise performance of reference voltage levels deteriorates
Solution Approach 1:
The patent extracts the reference voltage generation function from the indirect voltage divider approach and implements it directly using dedicated reference voltage sources. This separation allows the reference voltage sources to be optimized specifically for accuracy and low noise performance, while the rest of the circuit maintains simplicity. The reference voltage sources are taken out as independent components that directly provide stable reference levels to the ADC.
Solution Approach 2:
The patent introduces dedicated reference voltage sources as intermediary components between the supply voltage and the ADC. These reference voltage sources act as mediators that buffer and stabilize the reference voltage levels, isolating the ADC from supply voltage noise while maintaining accurate reference levels. This intermediary layer solves both the accuracy requirement and the simplicity requirement.
2Device complexity
If reference voltage levels are derived indirectly from supply voltage, then circuit complexity is reduced, but power consumption increases significantly
Solution Approach 1:
The patent extracts the power-intensive reference voltage generation function from the main signal path and implements it using efficient dedicated reference voltage sources. These specialized components are optimized for low power consumption while maintaining high accuracy, thereby reducing overall power consumption without increasing circuit complexity.
3Object-affected harmful factors
If high frequency noise is present on supply voltage, then the full signal swing of differential output voltage increases, but ADC linearity requirements become excessively high
Solution Approach 1:
The patent introduces dedicated reference voltage sources as intermediary components that buffer the ADC from supply voltage noise. These reference voltage sources filter and stabilize the reference voltage levels, preventing high frequency noise from coupling into the ADC input. This mediation reduces the noise impact on the differential output voltage, thereby lowering the linearity requirements for the ADC while maintaining measurement accuracy.
Data Source
AI summary
A sensor system is disclosed. The sensor system includes a first sensor path comprising a first sensing element and a second sensing element being connected in series between a first supply terminal and a second supply terminal and an intermediate node connected in between the first supply terminal and the second supply terminal, a second sensor path comprising a third sensing element and a fourth sensing element connected in series between the first supply terminal and the second supply terminal, a first reference node connected in between the first supply terminal and the second supply terminal, and a second reference node connected in between the first supply terminal and the second supply terminal, and a processing unit to receive an input signal from the intermediate node, a first reference signal from the first reference node, and a second reference signal from the second reference node.