MEMS Gyroscope Drive Circuit Phase Shift
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Solution Overview
Problem
MEMS gyroscope sensors in consumer, automotive, and aerospace/defense applications face challenges due to their large size and complexity, necessitating a reduction in the size and complexity of drive and sense electronics for effective three-axis acceleration detection.
Innovation Solution
A drive signal circuit for MEMS sensors is developed, featuring a phase-shift circuit that shifts input signals by 90 degrees, a comparator circuit with hysteresis, and a feedback loop to generate a self-oscillating signal, enabling reliable startup and high-Q reference drive signals for maintaining mechanical oscillation and resonance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional drive and sense electronics are used for MEMS gyroscopes, then the sensors can perform three-axis acceleration detection, but the size and complexity of the device become excessive
Solution Approach 1:
The patent combines the drive signal generation and phase shifting functions into a single integrated circuit. The phase shifter is directly coupled to the drive signal output, merging multiple functions (signal generation, phase shifting, and driving) into one compact unit, thereby reducing overall device complexity while maintaining three-axis detection capability
Solution Approach 2:
The drive signal circuit is designed to provide universal functionality for multiple axes by generating and phase-shifting signals that can be applied to different MEMS sensor elements. The circuit can serve multiple sensing axes through its ability to generate orthogonal drive signals, reducing the need for separate dedicated electronics for each axis
2Measurement precision
If a phase-shift circuit is added to achieve accurate 90-degree phase shifting, then the drive signal accuracy improves, but the device complexity increases
Solution Approach 1:
The patent replaces complex mechanical or analog phase-shifting mechanisms with an electronic phase-shifting circuit that uses signal processing techniques. The phase shifter electronically adjusts the phase of the drive signal by 90 degrees through circuit-based methods rather than mechanical means, achieving high precision with reduced physical complexity
Solution Approach 2:
The phase-shifting circuit achieves accurate 90-degree phase shifting by manipulating electrical parameters such as signal frequency, capacitance, and resistance. By changing these electrical parameters within the circuit, the desired phase shift is achieved without adding mechanical complexity to the system
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 solution provides reliable self-startup, accurate 90-degree phase shift, and high-Q reference drive signals, reducing noise and harmonic frequencies, thus enhancing the performance and efficiency of MEMS gyroscope sensors.
Implementation Method 1
A feedback loop extends from an output of the drive signal circuit to an input of the phase-shift circuit, wherein the feedback loop is configured to generate a self-oscillating signal at an output of the drive signal circuit
Implementation Method 2
a phase-shift circuit electrically coupled to the input and configured to phase shift an input signal by substantially ninety degrees
Implementation Method 3
a comparator circuit with hysteresis. An input of the comparator is electrically coupled to an output of the phase-shift circuit
Implementation Method 4
high-Q reference drive signals, reducing noise and harmonic frequencies, thus enhancing the performance and efficiency of MEMS gyroscope sensors
Data Source
AI summary
An apparatus includes a drive signal circuit for MEMS sensor. The drive signal circuit includes an input configured to receive a voltage signal representative of charge generated by the MEMS sensor, a phase-shift circuit electrically coupled to the input and configured to phase shift an input signal by substantially ninety degrees, and a comparator circuit with hysteresis. An input of the comparator is electrically coupled to an output of the phase-shift circuit and an output of the comparator circuit is electrically coupled to an output of the drive signal circuit. A feedback loop extends from the output of the drive signal circuit to the input of the phase-shift circuit and is configured to generate a self-oscillating signal at an output of the drive signal circuit. An output signal generated by the drive signal circuit is applied to a drive input of the MEMS sensor.