MEMS Gyroscope Sampler Amplifier Current Reduction
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Solution Overview
Problem
Existing microelectromechanical gyroscopes face challenges in reducing current consumption, particularly in portable devices, due to the continuous current draw from operational amplifiers used in gain tuning stages, which is critical for achieving controlled oscillation amplitude and frequency.
Innovation Solution
A microelectromechanical gyroscope design that employs a sampler and a transconductance operational amplifier in an open-loop configuration, allowing for separate sampling and amplification of sensing signals without direct coupling, thereby eliminating the need for a resistive feedback network and reducing current consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If closed-loop operational amplifiers with resistive feedback networks are used in gain tuning stages, then oscillation amplitude control precision is improved, but current consumption increases
Solution Approach 1:
The patent extracts and removes the resistive feedback network from the operational amplifier configuration. By eliminating the continuous current-drawing feedback path while maintaining the gain control functionality through alternative means, the invention achieves amplitude control without the harmful continuous current consumption associated with traditional closed-loop operational amplifiers.
Solution Approach 2:
The invention transitions from continuous current draw to periodic or pulsed action by using a clocked capacitor-based feedback mechanism. The operational amplifier operates in a sampled-data mode where feedback is applied periodically rather than continuously, significantly reducing average current consumption while maintaining control precision through synchronized sampling and holding.
2Stability of the object's composition
If operational amplifiers with resistive feedback networks are used, then oscillation frequency stability is improved, but device complexity increases
Solution Approach 1:
The patent replaces the traditional resistive feedback network (electrical/mechanical system) with a capacitor-based switched feedback mechanism controlled by clock signals. This substitution eliminates the need for precision resistors and complex feedback topology while achieving frequency stability through synchronous sampling and digital control techniques.
Solution Approach 2:
The invention changes the operating parameters of the operational amplifier from continuous analog feedback to discrete-time sampled feedback. By transforming the feedback mechanism from a continuous resistive network to a periodic capacitive switching system, the patent achieves frequency stability through parameter modulation rather than through complex continuous feedback circuits.
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 significantly saves current, making the gyroscope suitable for low-consumption applications and eliminating the need for additional components like closed-loop operational amplifiers, while maintaining controlled oscillation amplitude and frequency.
Implementation Method 1
the driving devices are based on resonator loops that include the movable mass and apply actuation forces through capacitively coupled fixed and movable actuation electrodes
Implementation Method 2
If the microstructure rotates around a rotation axis perpendicular to the driving axis, the movable mass is subject to an apparent or Coriolis force proportional to the rotation speed and perpendicular to both the driving axis and the rotation axis
Implementation Method 3
Displacements of the movable mass caused by the Coriolis force may be sensed relatively easily, for example through capacitively coupled fixed and movable sensing electrode systems
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A microelectromechanical gyroscope includes: a support structure (6); a driving mass (7) movable according to a driving axis (X); and an oscillating microelectromechanical loop (10), having a resonance frequency (fR) and a loop gain (GLOOP) and including the driving mass (7), a sensing interface (12), which senses a position of the driving mass (7), and a gain control stage (18), which maintains a modulus of the loop gain (GLOOP) at a unitary value at the resonance frequency (fR). The gain control stage (18) includes a sampler (20) and an transconductance operational amplifier (21) in an open-loop configuration. The sampler (20) acquires samples (VO*) of a loop signal (VO) from the sensing interface (12) in a first operative condition and transfers them to the transconductance operational amplifier (21) in a second operative condition. The sampler (20) decouples the transconductance operational amplifier (21) from the sensing interface (12) in the first operative condition and in the second operative condition.