Bridge Sensor Readout Using Shared Bias Current Powering
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Solution Overview
Problem
Existing sensor systems face significant power consumption issues when biasing and reading out multiple bridge sensors simultaneously, particularly consuming around 0.3 mA per sensor, which can add up to 30 mA for 100 sensors, posing a challenge for small ICs.
Innovation Solution
A sensor system where the amplifier is powered by part of the bias current of the bridge sensor, reusing the bias current for both the bridge sensor and the amplifier, thereby reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple bridge sensors are biased and read out simultaneously using separate current sources, then measurement accuracy and speed are improved, but power consumption increases significantly
Solution Approach 1:
The patent merges the bias current path and amplifier power supply into a single current source. The current source generates one bias current that simultaneously biases the bridge sensor and powers the amplifier, eliminating the need for separate current sources. This consolidation reduces the total current consumption from approximately 0.6 mA per sensor (0.3 mA for bias + 0.3 mA for amplifier) to approximately 0.3 mA per sensor, achieving significant power savings while maintaining simultaneous operation of multiple sensors.
Solution Approach 2:
The bias current source is designed to serve multiple functions simultaneously: it provides the excitation current for the bridge sensor, powers the amplifier operation, and establishes the operating point for the entire signal chain. This multi-functional current source replaces what would traditionally require separate dedicated current sources for each function, thereby reducing overall power consumption while maintaining system performance.
2Reliability
If separate current sources are used for biasing the bridge sensor and powering the amplifier, then signal integrity is maintained, but device complexity and power consumption increase
Solution Approach 1:
The patent combines what would traditionally be separate current sources into a single integrated current source that performs both biasing and amplifier powering functions. This reduces the number of independent components and simplifies the circuit architecture while maintaining the functional separation needed for signal integrity through proper internal circuit design.
Solution Approach 2:
The single current source is designed with multi-functionality to serve both the bridge sensor biasing and amplifier powering needs. By integrating multiple functions into one component, the overall device complexity is reduced while the universal design ensures that signal integrity requirements are met through appropriate internal signal path separation.
Data Source
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AI summary
A sensor system (100) for measuring a physical quantity. The sensor system (100) comprising: a bridge sensor (110) comprising at least two terminal pairs, a current source (150) for applying a bias current between the bias terminal pair, resulting in a differential sensor signal on a readout terminal pair (113, 114), wherein the differential sensor signal is indicative for the physical quantity, and an amplifier (120) comprising a first input node (121) and a second input node (122) for receiving the differential signal and at least one output node (123, 124), wherein the amplifier (120) is configured for amplifying the differential sensor signal and putting the resulting signal on the at least one output node (123, 124), wherein the sensor system (100) is configured such that, in operation, the amplifier (120) is powered by at least part of the bias current.