PCB Heat Spreader Layout for RF Filter Ground Inductance
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Solution Overview
Problem
Current radio frequency (RF) filters face challenges in operating at higher frequencies while maintaining optimal performance, particularly in terms of frequency band coverage and thermal management, as they often compromise thermal performance when embedding inductors in printed circuit boards (PCBs).
Innovation Solution
The proposed solution involves a radio frequency filter device that incorporates a piezoelectric layer with an interdigital transducer (IDT) and a printed circuit board (PCB) with multiple layers, including a configuration where at least one layer is split into physically separate portions with a gap, allowing for embedded inductors that minimize thermal impedance and enhance RF performance without degrading thermal management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If inductors are embedded in the PCB to improve RF filter performance and band-rejection, then RF capabilities are enhanced, but thermal performance degrades due to increased thermal impedance
Solution Approach 1:
The PCB layer is divided into two physically separate portions with a gap between them, allowing the inductor trace to extend across the gap. This segmentation enables the inductor to achieve longer trace length for better RF performance while the gap removes the obstructing copper that would create thermal impedance, thus resolving the contradiction between RF performance and thermal management.
2Reliability
If the PCB layer is split into separate portions to create embedded inductors, then band-rejection is improved, but device complexity increases
Solution Approach 1:
The split PCB layer serves multiple functions simultaneously: it creates the embedded inductor trace for band-rejection, provides thermal management by removing obstructing copper, and maintains mechanical integrity of the PCB. This multi-functionality achieves improved band-rejection without proportionally increasing device 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 configuration enables improved RF filter performance by maintaining thermal efficiency while supporting higher frequency operations, achieving better band-rejection and RF capabilities without compromising heat dissipation.
Implementation Method 1
a piezoelectric layer; an interdigital transducer (IDT) having interleaved fingers at the piezoelectric layer
Implementation Method 2
radio frequency filters using acoustic wave resonators
Implementation Method 3
a printed circuit board (PCB) comprising a plurality of layers comprising at least one layer that includes a first portion and a second portion that is physically separate from the first portion with a gap therebetween
Data Source
AI summary
A filter is provided that a piezoelectric layer, an interdigital transducers (IDT) having interleaved fingers at the piezoelectric layer, contact pads at the piezoelectric layer and electrically coupled to the IDT, and a printed circuit board (PCB). The PCB includes a plurality of layers including at least one layer that includes a first portion and a second portion that is physically separate from the first portion with a gap therebetween. Moreover, a plurality of electrical contacts are provided on a top layer of the plurality of layers that is facing the piezoelectric layer, with the plurality of electrical contacts electrically coupled to the plurality of contact pads, respectively.