Dual MEMS Resonator Temperature Sensing by Frequency Ratio
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Solution Overview
Problem
Current temperature sensing technologies face challenges in achieving high resolution and low power consumption while maintaining stability across a wide temperature range, with existing sensors often requiring high power and experiencing significant noise and non-linearity.
Innovation Solution
The development of a dual-resonator temperature sensor utilizing a pair of oscillators with different temperature coefficients and a frequency ratio engine that oversamples and decimates clock signals to generate a digital temperature-sense output, achieving low power consumption and high resolution through phase locking and quantization techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional temperature sensing technologies are used, then temperature measurement can be achieved, but power consumption is high and resolution is insufficient
Solution Approach 1:
The patent changes the operating parameters by using two resonators with different quality factors (Q1 and Q2) and different temperature coefficients, operating them at different amplitudes to achieve temperature-dependent frequency shifts that enable high-resolution measurement with low power consumption
Solution Approach 2:
The patent employs mechanical resonance of two MEMS resonators, utilizing their natural vibrational frequencies and quality factors to create temperature-sensitive oscillations that can be measured with high precision while consuming minimal power
2Measurement precision
If high power is used to improve signal strength, then measurement capability is enhanced, but noise and non-linearity increase significantly
Solution Approach 1:
The patent uses partial action by operating resonators at different amplitudes (one at higher amplitude, one at lower amplitude) to extract temperature information without requiring both to operate at high power levels, thereby reducing noise and non-linearity while maintaining measurement capability
Solution Approach 2:
The patent introduces frequency ratio as an intermediary parameter that relates the output frequencies of the two resonators, allowing temperature measurement through their ratio rather than absolute frequency values, which reduces the impact of noise and non-linearities
3Measurement precision
If temperature resolution is increased to 20°K with 100 Hz bandwidth, then measurement precision is improved, but power consumption must be controlled below 19 mW
Solution Approach 1:
The patent uses periodic action by oscillating the resonators at their natural frequencies and using frequency division techniques to downconvert the high-frequency oscillations to lower frequencies, enabling precise temperature measurement with reduced power consumption at the output stage
4Reliability
If frequency stability is improved to 100 ppb over -45°C to +105°C range, then reliability is enhanced, but device complexity increases due to dual-resonator implementation
Solution Approach 1:
The patent merges two resonators with different temperature characteristics into a single integrated device, using their combined frequency responses to achieve temperature compensation and high frequency stability across a wide temperature range, while the merging itself provides the temperature compensation mechanism
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 approach enables temperature resolution as low as 20°K with a bandwidth of 100 Hz while dissipating less than 19 mW, offering the best energy efficiency for integrated temperature sensors, with frequency stability as low as 100 ppb over a -45°C to +105°C range.
Implementation Method 1
a first resonator and a second resonator, each having a different quality factor and oscillating at different amplitudes
Implementation Method 2
achieving low power consumption and high resolution through phase locking and quantization techniques
Data Source
AI summary
In a high resolution temperature sensor, first and second MEMS resonators generate respective first and second clock signals and a locked-loop reference clock generator generates a reference clock signal having a frequency that is phase-locked to at least one of the first and second clock signals. A frequency-ratio engine within the MEMS temperature sensor oversamples at least one of the first and second clock signals with the reference clock signal to generate a ratio of the frequencies of the first and second clock signals.