BAW Resonator Pressure Sensing With Reference Resonator Compensation
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Solution Overview
Problem
Existing pressure sensors based on bulk acoustic wave (BAW) resonators face challenges in accurately measuring high pressures due to limited sensitivity and linearity in pressure-frequency shift correlation, which affects their reliability in high-pressure applications.
Innovation Solution
A BAW resonator pressure sensor apparatus is designed with a sensor BAW resonator and a reference BAW resonator on a die interface side, coupled with a control circuit die via an attachment layer, and an extended opening on the pressure contact side that translates external pressure onto the sensor BAW resonator, allowing for precise pressure measurement by comparing frequency shifts between the two resonators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a BAW resonator is used for pressure sensing, then the device can operate at high frequencies (100 MHz to 10 GHz), but the sensitivity and linearity in pressure-frequency shift correlation are limited for high-pressure applications
Solution Approach 1:
The pressure sensor is segmented into two distinct resonators: a sensor BAW resonator that is mechanically coupled to the pressure contact side for measuring pressure, and a reference BAW resonator that is acoustically isolated for temperature reference. This segmentation allows the sensor resonator to respond to pressure while the reference resonator compensates for temperature effects, improving measurement precision without sacrificing the high-frequency operation capability
Solution Approach 2:
An extended opening is introduced as an intermediary structure that translates external pressure applied to the pressure contact side onto the sensor BAW resonator. This mediator enhances the coupling between the pressure input and the resonator, improving the pressure-frequency shift correlation and enabling more accurate high-pressure measurements while maintaining the resonator's high-frequency operation
2Reliability
If pressure is applied directly to the BAW resonator, then the resonance frequency shifts, but the relationship becomes non-linear at high pressures reducing reliability
Solution Approach 1:
By segmenting the resonator system into sensor and reference components with distinct mechanical coupling arrangements, the sensor resonator can be optimized for linear pressure response while the reference resonator provides a stable frequency reference, improving overall measurement linearity and reliability at high pressures
Solution Approach 2:
The mechanical coupling parameters of the sensor BAW resonator are specifically optimized through the extended opening structure to enhance linearity in the pressure-frequency shift relationship. This parameter optimization ensures reliable and linear pressure measurement even at high pressure levels
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
The apparatus achieves high sensitivity with a linear response, suitable for high-pressure applications, with sensitivity measured at approximately 110 parts per million (ppm) per megapascal (MPa), enabling accurate pressure calculation based on resonance frequency shifts.
Implementation Method 1
A bulk acoustic wave (BAW) resonator device includes a piezoelectric material sandwiched between two electrodes
Implementation Method 2
A typical BAW resonator device resonates in the frequency range of roughly 100 MHz to 10 GHz
Implementation Method 3
an extended opening on the pressure contact side that translates external pressure onto the sensor BAW resonator
Implementation Method 4
when a BAW resonator device is put under mechanical pressure, its resonance frequency will shift
Data Source
AI summary
A pressure sensor apparatus is disclosed. The pressure sensor apparatus includes a bulk acoustic wave (BAW) die having a die interface side and a pressure contact side, a sensor BAW resonator and a reference BAW resonator disposed on the die interface side of the BAW die, a control circuit die coupled to the die interface side of the BAW die via an attachment layer, and an extended opening on the pressure contact side that extends into a depth of the BAW die and is generally aligned with the sensor BAW resonator, the extended opening being configured to translate an external pressure on the pressure contact side onto the sensor BAW resonator.