Differential Quadrature Driver for MEMS Gyroscope Error Correction
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Solution Overview
Problem
Quadrature error in Micro-Electrical Systems (MEMS) devices, particularly in MEMS gyroscopes, arises due to non-orthogonal drive and sense axes during manufacturing, leading to performance degradation and increased design constraints in signal processing.
Innovation Solution
A fully differential quadrature driver system using a high-voltage driver with programmable output settings for common mode voltage and differential voltage adjustments, combined with a low-voltage to high-voltage differential translator circuit, to correct quadrature errors in MEMS gyroscopes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fully differential high-voltage driver circuit is used to correct quadrature errors, then measurement precision and error correction capability are improved, but device complexity and circuit design requirements increase
Solution Approach 1:
The driver circuit is divided into separate functional blocks: a low-voltage differential translator stage that processes the quadrature error signal, and a high-voltage output stage that drives the correction electrodes. This segmentation allows each stage to be optimized independently - the LV stage for precision signal processing and the HV stage for effective actuation - thereby achieving high correction precision without requiring a single complex high-voltage differential circuit.
Solution Approach 2:
A low-voltage to high-voltage differential translator circuit serves as an intermediary between the low-voltage quadrature error signal and the high-voltage correction electrodes. This intermediate translator stage converts the LV differential signal to HV differential signals while maintaining signal integrity, enabling precise error correction without directly complexifying the high-voltage driver design.
2Stability of the object's composition
If common-mode feedback circuits are implemented to regulate voltage levels, then stability and common-mode rejection are improved, but device complexity increases
Solution Approach 1:
Common-mode feedback circuits are implemented in both the low-voltage translator stage and the high-voltage output stage. These feedback mechanisms continuously monitor and regulate the common-mode voltage levels, automatically correcting deviations to maintain stable operation. This feedback approach ensures high common-mode rejection ratio and stability without requiring complex manual calibration or adjustment mechanisms.
3Reliability
If high-voltage signals are used to correct quadrature errors, then correction effectiveness is improved, but power consumption and energy requirements increase
Solution Approach 1:
The circuit dynamically switches between low-voltage signal processing mode and high-voltage correction mode. The low-voltage differential translator handles the majority of signal processing at low power consumption, while the high-voltage output stage is activated only when quadrature correction is required. This dynamic operation minimizes overall power consumption while maintaining effective correction capability when needed.
Data Source
AI summary
According to an embodiment, a circuit for quadrate error correction is proposed. The circuit includes a set of first resistors receiving a demodulated low-voltage differential signal from gyroscope sense electrodes; an ICMFB circuit with adjustable current sinks maintaining a low-voltage input level by controlling current; an HV driver circuit creating a high-voltage differential output from the low-voltage input, supplied to gyroscope correction electrodes; a set of second resistors where the input-to-output differential gain is defined by their relative resistances; and an output common-mode feedback circuit adapting the high-voltage output to a low-voltage for the HV driver.