WLCSP Millimeter-Wave Passive Circuits for Lower RF Signal Loss
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Solution Overview
Problem
High-frequency signal losses occur in millimeter wavelength circuit operations due to significant losses between on-chip front-end devices and off-chip passive components, necessitating stringent design specifications for power amplifiers and low-noise amplifiers.
Innovation Solution
Integration of a front-end module circuit with a wafer-level chip-scale package (WLCSP) circuit on the same semiconductor die, incorporating passive components like matching networks, power combiners, and antennas, which reduces parasitic components and enhances signal transmission efficiency by using redistribution layers and under-bump metal for passive component fabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If off-chip passive components are used for millimeter wavelength circuits, then device complexity is reduced, but signal loss increases significantly
Solution Approach 1:
The patent merges the passive components (matching networks, power combiners, antennas) with the front-end device by fabricating them on the same semiconductor die using the WLCSP process. This integration eliminates the physical separation between active and passive components, thereby reducing signal loss while maintaining circuit functionality.
Solution Approach 2:
The patent transitions from traditional planar PCB layouts to a three-dimensional integrated structure where passive components are fabricated within the semiconductor die itself. This dimensional change enables closer proximity between components, reducing parasitic effects and signal loss in millimeter wavelength operations.
2Loss of energy
If on-chip passive components are integrated, then signal loss is reduced, but manufacturing complexity increases
Solution Approach 1:
The WLCSP process serves multiple functions simultaneously: it provides chip-scale packaging, creates interconnections through redistribution layers, and fabricates passive components (inductors, capacitors, matching networks) within the same die structure. This multi-functionality reduces the need for separate manufacturing steps for packaging and passive component fabrication.
Solution Approach 2:
The patent utilizes changes in material properties and fabrication parameters during the WLCSP process to create passive components with specific electrical characteristics. By controlling layer thickness, metal patterns, and via structures during standard CMOS fabrication, the passive components achieve required impedance and resonance properties without additional manufacturing complexity.
3Reliability
If passive components are fabricated using WLCSP process, then quality factor improves, but device complexity increases
Solution Approach 1:
The patent segments the semiconductor die into distinct functional regions: front-end active devices, passive components (matching networks, power combiners), and antenna elements. Each segment is optimized for its specific function while being fabricated using the same WLCSP process, allowing independent design optimization without increasing overall manufacturing complexity.
Data Source
AI summary
A device including a substrate, a front-end module circuit situated over the substrate and configured to provide radio frequency communications, and a wafer-level chip-scale package circuit situated over the front-end module circuit and connected to the front-end module circuit and configured to provide passive components for radio frequency communications.