MEMS Gyroscope Demodulator Phase Calibration
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Solution Overview
Problem
MEMS gyroscopes face challenges in accurately demodulating in-phase and quadrature signals due to significant quadrature errors caused by mechanical coupling, leading to measurement inaccuracies and increased complexity in existing solutions.
Innovation Solution
A demodulator that uses a noise-shaping modulator to generate quantized values for phase calibration, allowing the demodulating signal to be phase-locked with the input signal, thereby reducing the impact of quadrature components by varying the phase calibration value over time to approximate the ideal phase shift, effectively separating the in-phase and quadrature components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional demodulation methods are used to handle in-phase and quadrature signals, then the circuit structure is relatively simple, but significant quadrature errors occur due to mechanical coupling leading to measurement inaccuracies
Solution Approach 1:
The patent implements dynamic phase calibration by continuously adjusting the phase calibration value based on the relationship between in-phase and quadrature components. The demodulator dynamically updates the phase calibration value over time to track and compensate for varying quadrature errors, transforming a static calibration approach into a dynamic adaptive system that maintains measurement accuracy under changing operating conditions
Solution Approach 2:
The patent changes the phase calibration parameter dynamically to compensate for quadrature errors. By adjusting the phase calibration value based on the ratio of quadrature to in-phase components, the system modifies this critical parameter to cancel out the effects of mechanical coupling, thereby improving measurement precision without requiring complex hardware modifications
2Measurement precision
If phase calibration is performed with high precision to reduce quadrature errors, then measurement accuracy improves, but the computational complexity and processing time increase
Solution Approach 1:
The patent applies partial correction by focusing computational resources on the most significant error source - the quadrature component. Instead of performing exhaustive calibration across all possible error sources, the system calculates and applies correction based on the measured quadrature-to-in-phase ratio, achieving sufficient accuracy with reduced computational effort and faster processing
Solution Approach 2:
The demodulator performs self-calibration by using its own output signals (in-phase and quadrature components) to automatically adjust the phase calibration value. The system monitors its own performance and autonomously corrects phase errors without requiring external calibration equipment or manual intervention, reducing both time and resource requirements
Data Source
AI summary
A demodulator demodulates an in-phase component of an input signal which is in-phase and quadrature modulated. The demodulator includes a register storing a phase calibration value having an integer part and a fractional part. A noise-shaping modulator generates a succession of quantized values of integer type, the quantized values having a mean equal to the phase calibration value. A generating stage generates a demodulating signal phase locked with the input signal, the demodulating signal having a phase which depends linearly on the quantized values. A demodulating stage demodulates the input signal by means of the demodulating signal.