MEMS Gyroscope PLL with Dual Oscillators for Fast Low-Power Startup
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Solution Overview
Problem
Conventional MEMS gyroscope systems face high energy consumption, leading to long startup times when switching between operational and non-operational modes, as the driver circuit must maintain seismic mass oscillation regardless of measurement needs.
Innovation Solution
A phase-locked loop for the driver circuit that includes two oscillators with different energy consumption and noise properties, allowing for dynamic mode switching between active sensing and standby modes, using a low-noise oscillator for measurement and a low-energy oscillator when no measurements are detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the driver circuit maintains seismic mass oscillation continuously to enable rapid startup, then startup time is reduced, but energy consumption increases
Solution Approach 1:
The patent applies dynamics by making the oscillator configuration changeable based on operational mode. The system dynamically switches between a first oscillator configuration during active operation and a second oscillator configuration during standby mode, allowing optimal performance characteristics for each state rather than maintaining a fixed configuration.
Solution Approach 2:
The patent changes oscillator parameters (configuration, noise characteristics, energy consumption) based on operational requirements. The phase-locked loop system adjusts which oscillator is active depending on whether the gyroscope is in measurement mode or standby mode, optimizing the balance between startup speed and energy consumption.
2Measurement precision
If a low-noise oscillator is used for measurement operations, then data accuracy is improved, but energy consumption increases
Solution Approach 1:
The patent applies local quality by using different oscillator types in different operational contexts. The first oscillator with superior noise characteristics is used specifically during measurement operations where data accuracy is critical, while a different oscillator is used during standby operations where energy consumption is the primary concern.
Solution Approach 2:
The system dynamically selects which oscillator to use based on the operational mode. The phase-locked loop controller switches between oscillator configurations depending on whether measurement operations are active, allowing the system to optimize for either measurement precision or energy efficiency as needed.
3Use of energy by moving object
If the readout circuit is switched off during standby to reduce energy consumption, then energy savings are achieved, but measurement availability is reduced
Solution Approach 1:
The patent applies preliminary action by maintaining the seismic mass oscillation and the second oscillator configuration during standby mode, preparing the system in advance for rapid transition to measurement mode. This preliminary maintenance of oscillation state eliminates the need for lengthy startup sequences when measurement operations are initiated.
Data Source
AI summary
A phase-locked loop for a driver circuit for operating a MEMS gyroscope, including a seismic mass that is excitable into oscillations. The phase-locked loop including an input interface for receiving position signals that represent the present position of the oscillating seismic mass of the MEMS gyroscope, a phase detector for ascertaining the phase and frequency of the present oscillation movement of the seismic mass, based on the received position signals, at least two oscillators that are alternatively activatable, the alternatively activatable oscillators having different energy consumptions and/or different noise properties, and at least one output interface for outputting a signal that is provided by the oscillator that is presently activated.