Gyroscope FTR Feedback Loop for Bandwidth and Temperature Stability
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Solution Overview
Problem
Conventional MEMS gyroscope apparatus with high quality factor operates poorly in open-loop configurations and is sensitive to temperature, necessitating a signal processing circuit that extends bandwidth and provides large loop gain to null Coriolis force sensitivity.
Innovation Solution
A signal processing circuit with a negative feedback loop, comprising a demodulator, analog-to-digital converter, proportional-integral-derivative controller, digital-to-analog converter, and modulator, along with filters to reduce quantization noise, is implemented to achieve bandwidth extension and temperature insensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high quality factor is used in the gyroscope, then the operation in mode-matched condition is improved, but the open-loop configuration becomes difficult to operate
Solution Approach 1:
The patent implements a closed-loop configuration with negative feedback to replace the difficult-to-operate open-loop system. The feedback loop includes a demodulator, analog-to-digital converter, proportional-integral-derivative controller, digital-to-analog converter, and modulator that applies feedback force to the gyro structure, enabling stable operation of high quality factor gyroscopes.
Solution Approach 2:
The patent introduces signal processing circuits as intermediaries between the gyro structure and the output. These circuits include transimpedance amplifiers, demodulators, and digital signal processors that mediate the conversion of mechanical motion to electrical signals, making high quality factor operation practical.
2Reliability
If a high quality factor is used in the gyroscope, then the mode-matched condition is improved, but the temperature sensitivity increases
Solution Approach 1:
The closed-loop feedback system compensates for temperature-induced variations in quality factor. The proportional-integral-derivative controller adjusts the feedback gain to maintain consistent performance across temperature changes, eliminating the direct relationship between quality factor and temperature sensitivity.
Solution Approach 2:
The patent uses digital signal processing to dynamically adjust system parameters including gain and bandwidth compensation to counteract temperature effects. The proportional-integral-derivative controller modifies operating parameters in real-time to maintain stable performance despite temperature variations.
3Speed
If a negative feedback loop circuit is implemented, then the rate detection bandwidth is extended, but the device complexity increases
Solution Approach 1:
The patent combines multiple functions into integrated signal processing circuits. The demodulator, analog-to-digital converter, and digital signal processing functions are merged into a cohesive feedback loop system that achieves bandwidth extension without proportionally increasing complexity.
Solution Approach 2:
The patent replaces complex mechanical bandwidth extension mechanisms with electronic and digital signal processing solutions. The proportional-integral-derivative controller and digital filters achieve bandwidth control through electrical means rather than mechanical adjustments.
4Measurement precision
If filters are added to reduce quantization noise, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent uses digital filtering algorithms implemented in software or digital logic rather than complex analog filter circuits. The first filter and second filter are realized through digital signal processing techniques that reduce quantization noise without requiring additional physical filter components.
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 enables stable gain and insensitivity to temperature variations, effectively extending the rate detection bandwidth and nulling Coriolis force sensitivity, enhancing the gyroscope's operational stability and accuracy.
Implementation Method 1
The demodulator may include a first transimpedance amplifier, a voltage-to-voltage amplifier, and a first mixer configured to demodulate the converted voltage
Implementation Method 2
a first mixer configured to demodulate the converted voltage and outputting to the analog-to-digital converter
Implementation Method 3
a proportional-integral-derivative controller that is connected to the analog-to-digital converter
Implementation Method 4
a modulator configured to be electrically connected with the second electrode and to be electrically connected with the digital-to-analog converter
Implementation Method 5
The signal processing circuit may include a first filter configured to reduce a shaped quantization noise of the demodulated signal from the demodulator
Implementation Method 6
the second filter receives the analog signal from the digital-to-analog converter and is configured to reshape the analog signal. The second filter may filter a quantization noise from the reshaped analog signal
Implementation Method 7
there is a need to have the circuit, which could produce a large and stable gain by nulling the Coriolis force sensed
Data Source
AI summary
A signal processing circuit for a gyroscope apparatus is disclosed. The signal processing circuit includes a first electrode and a second electrode pairing with the first electrode. The signal processing circuit, being a negative feedback loop circuit, is configured to be connected with the first electrode and the second electrode and comprises a demodulator configured to convert a current from the first electrode into a voltage and demodulate the converted voltage to output a demodulated signal, an analog-to-digital converter configured to convert the demodulated signal from the demodulator into a digital signal, a proportional-integral-derivative controller that is connected to the analog-to-digital converter, a digital-to-analog converter configured to convert an output signal from the proportional-integral-derivative controller to an analog signal, and a modulator configured to be electrically connected with the second electrode and to be electrically connected with the digital-to-analog converter.