CMOS Sagnac RF Gyroscope Eliminates MEMS Noise
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Solution Overview
Problem
Existing gyroscopes, particularly those based on mechanical principles like MEMS, face challenges such as high Brownian noise, acoustic sensitivity, and high manufacturing costs due to the need for special fabrication processes, making them unsuitable for low-cost, high-performance applications in devices like smartphones and tablets.
Innovation Solution
A fully electronic gyroscope that exploits the Sagnac effect using radio-frequency signals propagating in a closed loop, eliminating the need for mechanical moving parts and leveraging standard CMOS fabrication processes to integrate all functions, including directional couplers and signal processing, within a single integrated circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If MEMS-based mechanical gyroscopes are used, then rotational sensing capability is achieved, but manufacturing cost increases due to special fabrication processes
Solution Approach 1:
The patent replaces the mechanical vibrating structure of MEMS gyroscopes with an electronic system based on the Sagnac effect. Instead of using mechanical resonators and Coriolis force detection, the invention uses radio-frequency signals propagating in opposite directions through a loop, where rotation induces a phase difference detectable by electronic components. This substitution eliminates the need for special MEMS fabrication processes and enables integration with standard CMOS technology.
Solution Approach 2:
The patent integrates multiple functions (signal generation, directional coupling, signal detection, and processing) into a single electronic system that can be fabricated using standard CMOS processes. The same fabrication process can be used for both the gyroscope and other digital logic circuits, making the device universally manufacturable with conventional semiconductor manufacturing infrastructure.
2Measurement precision
If MEMS-based mechanical gyroscopes are used, then rotational sensing is achieved, but noise increases due to Brownian motion
Solution Approach 1:
The patent eliminates mechanical moving parts that are susceptible to Brownian motion by replacing them with an electronic system based on electromagnetic wave propagation. The Sagnac effect-based electronic gyroscope uses RF signals in a transmission line loop, where the sensing mechanism relies on phase differences of electromagnetic waves rather than mechanical vibrations, thereby eliminating Brownian noise as a source of measurement error.
3Measurement precision
If MEMS-based mechanical gyroscopes are used, then rotational sensing is achieved, but acoustic sensitivity increases
Solution Approach 1:
The patent replaces the mechanical resonating structure with an electronic system that uses electromagnetic wave propagation in a transmission line. Since the sensing mechanism is based on the Sagnac effect with RF signals rather than mechanical vibration, the system becomes immune to acoustic interference that would otherwise couple into the mechanical structure and corrupt measurements.
4Ease of manufacture
If fully electronic Sagnac effect gyroscope is used, then manufacturing cost decreases through standard CMOS fabrication, but device complexity increases
Solution Approach 1:
The patent combines multiple electronic functions (RF signal generation, directional coupling, signal detection, and processing) into a single integrated circuit. By merging these functions into one chip using standard CMOS fabrication, the patent reduces manufacturing complexity compared to assembling separate components, while still achieving the performance benefits of the Sagnac effect-based electronic gyroscope.
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 solution provides a cost-effective, high-performance gyroscope with reduced noise, lower latency, immunity to acoustic interference, and integration capabilities with other CMOS ICs, enabling accurate three-dimensional rotational movement detection in compact, low-power devices.
Implementation Method 1
The apparatus and method of the present invention serve to detect and measure movement by exploiting the Sagnac effect that may be observed in radio-frequency signals that propagate in two opposite directions in a loop that undergoes rotation.
Data Source
AI summary
A radio frequency based electronic gyroscope function that may be incorporated in its entirety on a monolithic integrated circuit (IC). The detection and measurement of movement in a particular plane is based on the Sagnac effect as it applies to a radio frequency signal that propagates in two different directions in a loop that may be subject to rotational perturbation. In one embodiment, three mutually perpendicular loops that are incorporated into the same integrated circuit and are used to detect and measure movement in three planes (roll, pitch and yaw) thereby allowing a signal processing unit to quantify a general three dimensional movement. The gyroscope can be incorporated into an IC that is used in portable device, such as a mobile handset, to provide it with inertial navigation and movement detection and measurement capabilities.