MEMS Pressure Sensor Driver Architecture for Low-Power Sensing
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Solution Overview
Problem
Existing MEMS pressure sensors face challenges in reducing silicon area usage and power consumption while ensuring accurate temperature compensation and noise resistance in their analog processing chains.
Innovation Solution
A MEMS pressure sensor circuit design that utilizes a multiplexer to selectively switch between a pressure-sensitive and temperature-sensitive Wheatstone bridge, integrated with a voltage regulator arrangement and switch circuitry to generate a regulated voltage for accurate digitization, reducing the need for multiple amplifiers and minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three separate amplifiers are used to drive the Wheatstone bridges and regulate voltage, then the pressure and temperature sensing functions can be performed, but the silicon area occupied increases and power consumption increases
Solution Approach 1:
The patent merges the functions of three separate amplifiers into a single amplifier that can operate in different modes. The amplifier serves as both the bridge driver during pressure sensing and as the voltage regulator during temperature sensing, eliminating the need for separate amplifiers and reducing silicon area while maintaining sensing accuracy
Solution Approach 2:
The single amplifier is designed to perform multiple functions: it acts as a bridge driver amplifier during pressure sensing periods and as a voltage regulator during temperature sensing periods. This multi-functionality allows one component to replace three, reducing both area and power consumption
2Reliability
If three separate amplifiers are used to drive the Wheatstone bridges and regulate voltage, then the pressure and temperature sensing functions can be performed, but the power consumed increases
Solution Approach 1:
The patent merges the functions of three separate amplifiers into a single amplifier that can operate in different modes. The amplifier serves as both the bridge driver during pressure sensing and as the voltage regulator during temperature sensing, eliminating the need for separate amplifiers and reducing silicon area while maintaining sensing accuracy
Solution Approach 2:
The system operates in periodic cycles, alternating between pressure sensing periods and temperature sensing periods. During each period, the single amplifier performs the appropriate function (bridge driving or voltage regulation), eliminating the need for continuous operation of multiple amplifiers and reducing overall power consumption
3Area of stationary object
If a single amplifier is used for both bridge driving and voltage regulation, then the silicon area and power consumption are reduced, but the amplifier must switch between different functions
Solution Approach 1:
The system operates in periodic cycles, alternating between pressure sensing periods and temperature sensing periods. During each period, the single amplifier performs the appropriate function (bridge driving or voltage regulation), eliminating the need for continuous operation of multiple amplifiers and reducing overall power consumption
Solution Approach 2:
The amplifier operates in a feedback configuration where the output is fed back to the input through appropriate resistive dividers. During pressure sensing, the feedback path includes the Wheatstone bridge; during temperature sensing, it includes a voltage divider network. This feedback mechanism simplifies the switching control by using the same operational principle in both modes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design achieves reduced silicon area usage by 30% and power consumption by 70%, while ensuring accurate temperature compensation and rapid switching between pressure and temperature sensing cycles.
Implementation Method 1
a first Wheatstone bridge sensitive to pressure and configured to sense pressure applied thereto and generate the first voltage based upon the sensed pressure
Implementation Method 2
a second Wheatstone bridge sensitive to temperature and configured to sense temperature applied thereto and generate the second voltage based upon the sensed temperature
Data Source
AI summary
A MEMS pressure sensor includes a multiplexer passing a first-voltage or a second-voltage as output, an analog front-end (AFE) conditioning the output of the multiplexer to produce an ADC input, an analog-to-digital converter (ADC) digitizing the ADC input to produce an ADC output, a first Wheatstone-bridge sensitive to pressure and generating the first-voltage based upon the sensed pressure, a second Wheatstone-bridge sensitive to temperature generating the second-voltage based upon the sensed temperature, a voltage regulator using the first Wheatstone-bridge or the second Wheatstone-bridge in a feedback resistive-divider to generate a regulated-voltage, and control circuitry causing the voltage regulator to use the first Wheatstone-bridge during a pressure sensing period, and causing the voltage regulator to use the second Wheatstone-bridge during a temperature sensing period. The AFE and ADC are powered by the regulated-voltage, and the AFE and ADC use a feedback-voltage generated by the feedback resistive-divider as a reference-voltage.