Implant RF Telemetry Filter Using SMR Resonators for Miniaturization
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Solution Overview
Problem
Current RF telemetry systems in active medical devices face challenges such as large component size, high manufacturing costs, significant insertion losses, and difficulty in miniaturization due to the use of Surface Acoustic Wave (SAW) and Thin Film Bulk Acoustic Resonator (FBAR) filters, which are not well-suited for implanted devices with limited space and require complex manufacturing processes.
Innovation Solution
The implementation of Solidly Mounted Resonator (SMR) type volume acoustic wave resonators with Bragg acoustic reflector insulation for RF telemetry circuits, allowing for a monolithic integration of RF transmitter/receivers and band rejection filters, enabling miniaturization, reduced manufacturing costs, and improved performance by eliminating the need for additional components and processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Surface Acoustic Wave (SAW) resonators are used for RF telemetry filters, then high selectivity and abrupt band rejection characteristic are achieved, but component size becomes relatively large
Solution Approach 1:
The patent replaces Surface Acoustic Wave (SAW) resonators with Solidly Mounted Resonators (SMR) of the FBAR type. This substitution transitions from surface wave propagation to bulk acoustic wave resonance in a thin film structure, achieving comparable filter selectivity while dramatically reducing component size to fit implanted medical devices.
2Measurement precision
If SAW resonators are used in implanted devices, then high filter selectivity is achieved, but manufacturing complexity and cost increase due to discrete component bonding
Solution Approach 1:
The patent merges the FBAR resonator fabrication with the underlying electronic circuit manufacturing process. The resonator is formed as a thin film structure directly on the circuit substrate, eliminating separate discrete component bonding steps and reducing manufacturing complexity while maintaining high filter selectivity.
3Measurement precision
If SAW resonators are used for RF telemetry, then excellent filter selectivity is achieved, but insertion losses increase significantly
Solution Approach 1:
The patent replaces SAW resonators with FBAR-type Solidly Mounted Resonators, substituting surface acoustic wave propagation with bulk acoustic wave resonance. This mechanical system substitution reduces energy dissipation through surface effects and coupling losses, achieving comparable selectivity with significantly lower insertion losses.
4Volume of moving object
If FBAR resonators are used instead of SAW resonators, then component size is reduced and insertion losses are lower, but micro-machining of thin movable membrane becomes difficult and introduces scrap
Solution Approach 1:
The patent merges the FBAR resonator fabrication process with the standard electronic circuit manufacturing process. The thin film resonator structure is formed using deposition and patterning techniques that are already part of semiconductor fabrication, eliminating the need for separate complex micro-machining steps and reducing scrap.
5Volume of moving object
If FBAR resonators with movable membrane are used, then smaller size is achieved, but hermetic enclosure becomes necessary to prevent particle deposition and frequency drift
Solution Approach 1:
The patent integrates the FBAR resonator fabrication directly onto the electronic circuit substrate, forming a solidly mounted structure that eliminates the need for hermetic enclosures. The resonator is formed as part of the circuit assembly process, and the solid mounting structure inherently protects against particle deposition and frequency drift without requiring additional enclosure steps.
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, compact, and efficient RF telemetry system capable of operating across multiple frequency bands, optimizing data transmission by selecting the best band for propagation and reducing power consumption, while minimizing insertion losses and manufacturing complexities.
Implementation Method 1
SMR type with Bragg acoustic reflector insulation
Implementation Method 2
volume acoustic waves BAW resonator
Data Source
AI summary
RF telemetry for an active medical device such as active implant or programmer for such implant. The device includes at least one RF antenna (14), and at least one RF telemetry transmitter/receiver (44) with, for coupling to the antenna, an associated band rejection filter (54). The band rejection filter (54) comprises at least one volume acoustic wave BAW resonator (40) of the SMR type with insulation by Bragg acoustic reflector (42). The device can be a multi-band device comprising a plurality of RF transmitters/receivers (12, 44) operating in respective distinct bands of frequencies such as the 402˜405-MHz, 863˜870-MHz, 902˜928-MHz and 2.4-GHz bands or by UWB transmission.