MEMS Gyroscope Drive Frames for Common Mode Noise Cancellation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing MEMS gyro sensors face challenges in accurately detecting angular acceleration due to limitations in displacement detection and common mode noise cancellation.
Innovation Solution
The MEMS device incorporates a sensor unit with a coupling spring that mechanically couples two drive frames to vibrate in opposite phases, and a fully differential circuit configuration that includes multiple capacitors to cancel common mode noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single drive frame is used for detection, then the device structure is simple, but common mode noise cannot be effectively canceled and measurement precision deteriorates
Solution Approach 1:
The single drive frame is segmented into two separate drive frames (first drive frame and second drive frame) that operate in opposite phases. This segmentation enables differential measurement to cancel common mode noise while maintaining relatively simple device structure through the use of identical replicated components.
Solution Approach 2:
The two drive frames are configured to vibrate in opposite phases, creating a counterbalancing effect where the noise signals from each frame cancel each other out. This anti-phase operation serves as a mechanical implementation of noise cancellation, improving measurement precision without significantly increasing device complexity.
2Ease of operation
If drive frames are not synchronized, then the device operation is simple, but detection accuracy deteriorates due to phase mismatch
Solution Approach 1:
The drive frames are excited at a specific resonant frequency to maintain stable periodic vibrations. This periodic action ensures consistent phase relationships between the drive frames, improving detection accuracy while keeping the operation simple through automated frequency control.
Solution Approach 2:
A feedback mechanism is implemented to monitor and adjust the phase relationship between the two drive frames. This feedback control ensures the drive frames remain synchronized in opposite phases, maintaining high detection accuracy without requiring complex manual adjustment.
3Adaptability or versatility
If coupling spring stiffness is low, then the drive frames can move freely, but synchronization control becomes difficult and measurement precision worsens
Solution Approach 1:
The coupling spring stiffness is designed to be dynamically adjustable or optimized for the operating frequency range. This allows the system to maintain appropriate coupling strength for synchronization while permitting sufficient movement freedom for the drive frames to respond to external angular acceleration inputs.
Solution Approach 2:
The stiffness parameter of the coupling spring is carefully selected and potentially adjusted to achieve optimal balance between synchronization control and movement freedom. By tuning this parameter, the system achieves both adequate coupling for phase synchronization and sufficient compliance for detecting external stimuli.
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 enables accurate detection of angular acceleration by effectively canceling common mode noise and synchronizing the drive frames, thereby improving the precision of angular acceleration measurement.
Implementation Method 1
a coupling spring connecting the first drive frame and the second drive frame
Implementation Method 2
a first excitation unit that uses electrostatic excitation to excite the first drive frame in the first direction
Implementation Method 3
when the angular acceleration in an in-plane direction parallel to a first direction acts on an element vibrating in the first direction, the Coriolis force displaces the element in a second direction orthogonal to the first direction
Implementation Method 4
The displacement of the element in the second direction is detected as a change in electrostatic capacitance
Data Source
AI summary
Provided is a MEMS device including a substrate, a recessed portion, and a sensor unit positioned in the recessed portion, in which the sensor unit includes a first drive frame, a second drive frame, a first detection frame, a second detection frame, a first fixation frame, a second fixation frame, a first excitation unit, a second excitation unit, a first movable electrode, a second movable electrode, a first fixation electrode, a second fixation electrode, a third fixation electrode, and a fourth fixation electrode, in which each of the first fixation electrode and the second fixation electrode is coupled to the first fixation frame through an isolation joint, the isolation joint being configured to electrically insulate and mechanically couple two members, and each of the third fixation electrode and the fourth fixation electrode is coupled to the second fixation frame through the isolation joint.