Gyro Sensor Signal Processing Circuit Noise Reduction
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Solution Overview
Problem
Existing gyro sensors face challenges in reducing noise while maintaining detection accuracy and minimizing circuit area, as noise folds back to the DC band due to sampling processes, requiring increased sampling frequencies that necessitate additional circuitry like phase locked loops, which increase circuit size.
Innovation Solution
A signal processing circuit that includes a current/voltage conversion section, phase shift section, drive amplitude control section, reference signal generation, clock signal generation, and switched capacitor filter, which generates a clock signal with a frequency twice the drive frequency using a phase difference, eliminating the need for a multiplying circuit and reducing noise without increasing circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the sampling frequency of the SCF is increased to reduce noise folding back to the DC band, then noise reduction is improved, but additional circuitry (multiplying circuit/PLL) is required which increases circuit area
Solution Approach 1:
The patent changes the clock signal frequency parameter from equal to the drive frequency to twice the drive frequency. This parameter change allows the SCF to reduce noise folding back to the DC band without requiring additional multiplying circuits, thus achieving noise reduction while maintaining compact circuit area.
Solution Approach 2:
The patent dynamically generates the clock signal at twice the drive frequency by utilizing the phase difference between the reference signal and the switch control signal. This dynamic approach eliminates the need for static additional circuitry like PLL, achieving flexible frequency multiplication within the existing circuit framework.
2Device complexity
If the sampling frequency is set to equal the drive frequency to meet reduction in size demands, then circuit area is reduced, but noise folds back to the DC band reducing detection accuracy
Solution Approach 1:
The patent changes the clock signal frequency parameter from equal to the drive frequency to twice the drive frequency. This parameter change allows the SCF to reduce noise folding back to the DC band without requiring additional multiplying circuits, thus achieving noise reduction while maintaining compact circuit area.
Solution Approach 2:
The patent converts the phase difference between the reference signal and switch control signal, which could be considered a harmful factor affecting signal accuracy, into a beneficial resource for generating the clock signal at twice the drive frequency. This eliminates the need for additional circuitry while improving noise performance.
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 configuration effectively reduces noise while maintaining detection accuracy and minimizing circuit size by generating a clock signal twice the drive frequency, thereby reducing noise folding into the DC band and improving detection sensitivity.
Implementation Method 1
a current/voltage conversion section that converts an oscillation current of the vibrator into a voltage
Implementation Method 2
a phase shift section that shifts a phase of a signal that has been converted into a voltage by the current/voltage conversion section
Implementation Method 3
full-wave rectifies a signal that has been shifted in phase by the phase shift section based on the switch control signal
Implementation Method 4
a synchronous detection section that synchronously detects a signal that includes the detection signal of the vibrator based on the reference signal
Implementation Method 5
a switched capacitor filter that filters a signal that has been synchronously detected by the synchronous detection section based on the clock signal
Implementation Method 6
causes a vibrator to oscillate
Implementation Method 7
a vibrating gyro sensor that utilizes the resonance phenomenon of a crystal vibrator
Data Source
AI summary
A signal processing circuit includes an I/V conversion circuit (current/voltage conversion section) that converts an oscillation current of a vibrator into a voltage, an RC filter (phase shift section) that shifts a phase of the output signal of the I/V conversion circuit, a full-wave rectifier (part of a drive amplitude control section) that binarizes a signal that has been shifted in phase to generate a switch control signal, a comparator (reference signal generation section) that generates a reference signal for synchronous detection based on the output signal of the I/V conversion circuit, and an EXOR circuit (clock signal generation section) that generates a clock signal for a switched capacitor filter (SCF) that has a frequency twice a frequency of a drive signal based on a phase difference between the reference signal and the switch control signal.