MEMS Pressure Sensor Driver Architecture With Switched Bridge Feedback
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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 control circuitry to generate a regulated reference voltage, reducing the need for multiple amplifiers and minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three separate amplifiers are used for voltage regulation, pressure sensing, and temperature sensing, then each function can be performed independently, but the silicon area consumption and power consumption increase
Solution Approach 1:
The single amplifier is designed to perform multiple functions by switching between different configurations: voltage regulation during both pressure and temperature sensing, pressure signal amplification, and temperature signal amplification. This multi-functional design eliminates the need for separate amplifiers for each function, reducing silicon area and power consumption while maintaining functional independence through temporal separation of operations
Solution Approach 2:
The system employs periodic switching between pressure sensing mode and temperature sensing mode. During pressure sensing, the amplifier regulates voltage for the pressure bridge and amplifies its output. During temperature sensing, it regulates voltage for the temperature bridge and amplifies its output. This periodic operation allows one amplifier to handle all amplification and regulation tasks that previously required three separate amplifiers
2Reliability
If three separate amplifiers are used for voltage regulation, pressure sensing, and temperature sensing, then each function can be performed independently, but the power consumption increases
Solution Approach 1:
The single amplifier is designed to perform multiple functions by switching between different configurations: voltage regulation during both pressure and temperature sensing, pressure signal amplification, and temperature signal amplification. This multi-functional design eliminates the need for separate amplifiers for each function, reducing silicon area and power consumption while maintaining functional independence through temporal separation of operations
Solution Approach 2:
The system employs periodic switching between pressure sensing mode and temperature sensing mode. During pressure sensing, the amplifier regulates voltage for the pressure bridge and amplifies its output. During temperature sensing, it regulates voltage for the temperature bridge and amplifies its output. This periodic operation allows one amplifier to handle all amplification and regulation tasks that previously required three separate amplifiers
3Adaptability or versatility
If different reference voltages are used for pressure and temperature sensing, then each sensing can be optimized independently, but the ADC accuracy during temperature sensing decreases due to noise from bridge driving
Solution Approach 1:
The system employs periodic switching between pressure sensing mode and temperature sensing mode. During pressure sensing, the amplifier regulates voltage for the pressure bridge and amplifies its output. During temperature sensing, it regulates voltage for the temperature bridge and amplifies its output. This periodic operation allows one amplifier to handle all amplification and regulation tasks that previously required three separate amplifiers
Solution Approach 2:
The voltage regulator arrangement uses feedback from the selected Wheatstone bridge to maintain accurate reference voltages. During temperature sensing, the feedback mechanism ensures that the reference voltage is stable and not affected by noise from bridge driving, thereby maintaining ADC accuracy while still allowing independent optimization of each sensing mode
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
Figure 1~2
Figure 3~4
Figure 5
AI summary
A MEMS pressure sensor (100) includes a multiplexer (14) passing a first-voltage (ΔVP) or a second-voltage (ΔVT) as output, an analog front-end, AFE, (15) conditioning the output of the multiplexer to produce an ADC input, an analog-to-digital converter, ADC, (16) digitizing the ADC input to produce an ADC output (OUT), a first Wheatstone-bridge (11) sensitive to pressure and generating the first-voltage based upon the sensed pressure, a second Wheatstone-bridge (12) 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 (17) 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.