Temperature-Controlled Acoustic Resonator for Frequency Drift Reduction
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Solution Overview
Problem
Acoustic resonators in electronic devices experience frequency drift due to physical stresses, particularly from differential forces caused by temperature changes and packaging materials, leading to significant frequency shifts that exceed tolerance limits in high-accuracy applications.
Innovation Solution
The implementation of an acoustic resonator structure with an integrated heater and temperature feedback circuit, along with a pedestal that mechanically isolates the resonator and tethers that suspend it over a trench, minimizes physical stress and maintains a constant temperature, thereby reducing frequency drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the acoustic resonator is mounted on a PCB in a chip-scale package, then the device can be integrated into electronic systems, but frequency drift occurs due to physical stress from differential forces during heating or cooling
Solution Approach 1:
The device is segmented into functionally independent components: the acoustic resonator is mechanically isolated from the PCB through the chip-scale package structure, allowing the resonator to operate independently from thermal and mechanical stresses of the host system
Solution Approach 2:
The chip-scale package acts as an intermediary between the PCB and the acoustic resonator. It provides mechanical support and electrical connection while isolating the resonator from differential stress caused by PCB thermal expansion, thus preventing frequency drift
2Reliability
If temperature control is implemented using a heater and feedback circuit, then frequency stability is improved, but device complexity increases
Solution Approach 1:
A temperature feedback control system is implemented where a temperature sensor monitors the resonator temperature and a feedback circuit adjusts the heater power accordingly. This closed-loop control maintains the resonator at its turnover temperature, compensating for frequency drift caused by temperature variations
Solution Approach 2:
The system dynamically changes the temperature parameter of the resonator by applying controlled heating. By adjusting the temperature to maintain operation at the turnover point, the frequency stability is improved despite the added control complexity
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 effectively stabilizes the center frequency of acoustic resonators, ensuring they meet the stringent frequency tolerance requirements of high-accuracy electronic devices by isolating them from external forces and maintaining a stable temperature.
Implementation Method 1
The implementation of an acoustic resonator structure with an integrated heater and temperature feedback circuit
Implementation Method 2
temperature feedback circuit
Data Source
AI summary
An acoustic resonator device includes an annular acoustic resonator, a heater coil and a heat sensor. The annular acoustic resonator is positioned over a trench formed in a substrate of the acoustic resonator device. The heater coil is disposed around a perimeter of the annular acoustic resonator, the heater coil including a resistor configured to receive a heater current. The heat sensor is configured to adjust the heater current in response to a temperature of the heater coil. A feedback circuit is used to control a temperature of the acoustic resonator device.