Compact RF Harmonic Filter Using Single IPD Loop Inductor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional RF harmonic filters using integrated passive device (IPD) technology are bulky due to the presence of two loop inductors, which hinders miniaturization efforts in high-frequency cellular phone components without increasing manufacturing cost or complexity.
Innovation Solution
An RF harmonic filter is designed as an IPD with only one loop inductor, integrating harmonic resonance and impedance matching circuits to reduce the device footprint, eliminating one loop inductor and combining matching circuit functionalities with resonance circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional IPD implementations use two loop inductors for harmonic filtering, then the filtering function is achieved, but the device footprint increases
Solution Approach 1:
The patent combines two separate loop inductors into a single shared loop inductor that is common to both the first and second harmonic resonance circuits. This merging reduces the component count and physical footprint while maintaining the harmonic filtering function through shared resonance paths.
Solution Approach 2:
The single loop inductor serves multiple functions by being shared between two different harmonic resonance circuits. It simultaneously participates in filtering different harmonic frequencies (e.g., 2nd and 3rd harmonics) through different resonance paths, making it a multi-functional component.
2Reliability
If distinct input and output impedance matching circuit elements are used, then impedance matching is achieved, but the overall device size increases
Solution Approach 1:
The patent integrates impedance matching functions directly into the existing harmonic resonance circuits rather than using separate matching circuits. The resonance circuits are designed to provide both harmonic filtering and impedance matching, combining multiple functions into unified circuit structures.
Solution Approach 2:
The harmonic resonance circuits serve dual purposes: they filter specific harmonic frequencies while simultaneously providing impedance matching at the input and output ports. This multi-functionality eliminates the need for dedicated matching circuits and reduces overall device size.
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 design achieves a compact, low-cost RF harmonic filter with reduced size and packaging requirements while maintaining effective frequency rejection of second, third, and fourth harmonic frequencies, as demonstrated by simulated insertion loss characteristics.
Implementation Method 1
a harmonic resonance circuit formed on the substrate, where the harmonic resonance circuit includes the IPD loop inductance
Data Source
AI summary
A radio frequency (“RF”) harmonic filter circuit as disclosed herein is fabricated using integrated passive device (“IPD”) technology. The RF harmonic filter circuit is configured to provide second, third, and fourth harmonic rejection while providing good input and output impedance matching. The RF harmonic filter circuit employs only one IPD loop inductance (preferably used for a second harmonic resonance circuit), which results in a significant die/package size reduction. The RF harmonic filter circuit also employs a combined circuit that performs input and/or output impedance matching and third harmonic rejection.