MEMS Timing Source Using Resonator Frequency Translation
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Solution Overview
Problem
MEMS devices face challenges in generating an accurate clock signal without external quartz crystals, as existing oscillator circuits are sensitive to temperature changes and cost constraints, necessitating a cost-effective internal timing solution.
Innovation Solution
Utilizing the oscillating MEMS structure as a reference signal for a frequency translator circuit, such as PLL or DLL, to generate an accurate clock source for supporting electronics, minimizing additional cost and temperature dependence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a relaxation oscillator circuit is used to generate the clock signal, then the device complexity is reduced and power consumption is lowered, but the timing accuracy deteriorates due to temperature sensitivity of resistive and capacitive components
Solution Approach 1:
The patent replaces the electrical relaxation oscillator circuit with a mechanical resonating MEMS structure as the frequency-determining element. The MEMS resonator uses physical mechanical resonance to generate the clock signal, substituting the electrical RC time constant mechanism with a mechanical vibrating structure that has superior temperature stability and frequency accuracy.
Solution Approach 2:
The patent changes the fundamental parameter used for frequency determination from electrical components (resistors and capacitors whose values drift with temperature) to a mechanical resonator's physical dimensions and material properties, which remain stable across temperature ranges. This parameter change enables accurate timing without requiring complex temperature compensation circuits.
2Measurement precision
If a crystal filter is used to provide an accurate clock signal, then the timing accuracy is improved, but the device cost and size increase
Solution Approach 1:
The patent makes the MEMS resonating structure serve dual functions: it acts as both the primary sensing element for the inertial measurement and as the frequency-determining element for the clock signal generation. This multi-functionality eliminates the need for separate quartz crystals or crystal filters, reducing both device size and cost while maintaining accurate timing.
Solution Approach 2:
The patent merges the timing function with the existing MEMS resonating structure by using the same physical vibration that provides the inertial signal also to drive the frequency translator circuit. This consolidation integrates the clock generation function into the existing MEMS device architecture without adding separate timing components.
3Reliability
If external quartz crystals are used for accurate timing, then the clock signal stability is improved, but the device cost increases
Solution Approach 1:
The patent enables the MEMS device to generate its own accurate clock signal using its internal resonating structure, eliminating the need for external quartz crystals. The device serves itself by using the same MEMS resonator for both sensing and timing functions, thereby reducing component count and manufacturing cost while maintaining reliable clock signal stability.
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
Provides a stable and accurate clock signal for MEMS devices, suitable for navigation and other applications, by leveraging the stable oscillation frequency of the MEMS structure, which is temperature-resistant and cost-effective.
Implementation Method 1
A method of providing an accurate clock source for electronics that support a MEMS device which has a vibrating MEMS structure
Data Source
AI summary
A system and method is disclosed that provides a technique for generating an accurate time base for MEMS sensors and actuators which has a vibrating MEMS structure. The accurate clock is generated from the MEMS oscillations and converted to the usable range by means of a frequency translation circuit.