Gyroscope Phase-Offset Error Correction via I/Q Demodulation
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Solution Overview
Problem
Existing MEMS gyroscope circuits suffer from offset drift errors due to manufacturing tolerances and fluctuating operating temperatures, leading to phase-offset errors that result in inaccurate signal measurements.
Innovation Solution
A signal processing circuit that includes an in-phase quadrature-phase (I/Q) demodulator and a phase-offset error correction module, which measures both in-phase and quadrature-phase signals, calculates and applies a scaling factor to subtract the quadrature-phase signal from the in-phase signal, thereby reducing or eliminating phase-offset errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex closed-loop feedback circuits are used to mitigate offset drift errors, then measurement accuracy is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts and corrects the phase offset error component separately from the main signal processing path. By identifying the quadrature signal as the source of phase offset errors and processing it through a dedicated correction module, the system removes harmful effects without requiring complex feedback circuits, thus maintaining measurement accuracy while reducing circuit complexity
Solution Approach 2:
The signal processing is segmented into distinct functional modules: I/Q demodulation, phase offset error measurement, scaling factor calculation, and corrected signal generation. This modular approach allows the phase correction function to be implemented independently, avoiding the need for complex integrated feedback circuits while improving measurement precision
2Measurement precision
If complex closed-loop feedback circuits are used to mitigate offset drift errors, then measurement accuracy is improved, but power consumption increases
Solution Approach 1:
By extracting the phase offset correction function into a separate measurement and processing module, the system eliminates the need for continuous high-power feedback operations. The correction is applied based on measured phase offset values, reducing power consumption while maintaining measurement accuracy
Solution Approach 2:
The system performs preliminary measurement of the phase offset error and calculates the scaling factor in advance, before the actual measurement process. This preliminary action allows the main measurement to proceed with simpler, lower-power processing while still achieving high accuracy through pre-computed correction parameters
3Measurement precision
If phase-offset error correction is applied, then signal measurement accuracy is improved, but circuit complexity increases
Solution Approach 1:
The patent introduces an intermediary scaling factor that simplifies the correction process. Instead of implementing complex real-time feedback control, the system uses a calculated scaling factor applied to the quadrature signal to compensate for phase offset errors, achieving improved measurement accuracy with minimal additional circuit complexity
Solution Approach 2:
The system creates a corrected copy of the original signal by combining the in-phase signal with the scaled quadrature signal. This copying approach allows the original signal processing path to remain simple while generating an accurate corrected output, avoiding the need to redesign the entire circuit
Data Source
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AI summary
A circuit for processing signals from a gyroscope includes a first that generates an in-phase demodulated signal and a second demodulator that generates a quadrature-phase demodulated signal with reference to in-phase and quadrature-phase modulated signals, respectively, from the gyroscope. The circuit includes a digital processor that receives the demodulated in-phase and quadrature phase signals from the demodulators and generates an output signal corresponding to a rotation of the gyroscope along a predetermined axis with reference to the in-phase demodulated signal and the quadrature-phase demodulated signal to remove a portion of the quadrature-phase signal from the in-phase signal.