MEMS Sensor Calibration Circuit for Temperature and Supply Variation
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Solution Overview
Problem
Microelectromechanical systems (MEMS) sensors are sensitive to minor variations in temperature and supply voltage, leading to inconsistent circuit performance, which existing calibration methods fail to adequately address.
Innovation Solution
A temperature and power supply calibration system using a differential amplifier circuit that combines temperature and supply voltage information, allowing for compensation of sensor outputs through a ratio of base-emitter voltages, eliminating the need for a traditional bandgap voltage reference and enabling simultaneous detection of temperature and supply voltage variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional bandgap voltage reference is used for temperature calibration, then temperature compensation can be achieved, but device complexity and manufacturing precision requirements increase
Solution Approach 1:
The patent extracts the temperature sensing function from the traditional bandgap voltage reference circuit by using a separate temperature sensor to measure junction temperature. This extracted temperature information is then used to calculate compensation factors, simplifying the overall calibration circuit architecture while maintaining measurement precision.
Solution Approach 2:
The microcontroller unit serves multiple functions: it reads temperature sensor data, calculates compensation factors based on stored calibration parameters, and applies corrections to sensor readings. This multi-functional approach eliminates the need for complex dedicated compensation circuits, reducing device complexity while achieving accurate temperature compensation.
2Reliability
If separate temperature and voltage calibration methods are used, then each parameter can be compensated independently, but the overall calibration system complexity increases
Solution Approach 1:
The patent combines temperature compensation and supply voltage compensation into a single integrated calibration system. Both compensation factors are calculated using the same microcontroller unit and stored in the same memory structure, allowing independent compensation of each parameter while maintaining a unified, simplified system architecture.
Solution Approach 2:
The system uses parameter storage in memory to represent different temperature and voltage conditions. By storing calibration parameters for various operating conditions and selecting the appropriate parameters based on current sensor readings, the system achieves adaptive compensation without requiring complex real-time calculation circuits for each parameter.
3Adaptability or versatility
If MEMS sensors operate across varying temperature and supply voltage conditions, then adaptability to different environments is improved, but output consistency and measurement precision deteriorate
Solution Approach 1:
The patent implements feedback compensation by continuously monitoring temperature and supply voltage through dedicated sensors, calculating the deviation from nominal conditions, and applying correction factors to the MEMS sensor output. This closed-loop feedback mechanism maintains measurement precision across varying operating conditions by dynamically compensating for environmental effects.
Solution Approach 2:
The system performs preliminary calibration during manufacturing where compensation parameters for different temperature and voltage conditions are measured and stored in memory. During operation, the microcontroller selects the appropriate pre-calculated compensation parameters based on current conditions, enabling quick adaptation without real-time complex calculations and maintaining output consistency across the operating range.
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
This solution effectively reduces the sensitivity of MEMS sensors to temperature and supply voltage changes, providing accurate and stable output by applying linear or higher-order correction factors to the sensor data, thereby enhancing the reliability of MEMS sensor performance.
Implementation Method 1
a temperature sensor to sense temperature information and compensate for variation in an output signal due to temperature
Implementation Method 2
a difference between a positive and negative supply, or a change (Δ) in said differences can be determined and subsequently used to compensate the output
Data Source
AI summary
This document discusses, among other things, a temperature and power supply calibration system configured to compensate for temperature and supply voltage variation in MEMS or other circuits using representations of positive and negative supply voltages and first and second base-emitter voltages, wherein the second base-emitter voltage is a scaled representation of the first base-emitter voltage.