InFO Antenna Ground Plane for Signal Reflection and Isolation
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Solution Overview
Problem
Existing integrated antennas face challenges in efficiently transmitting signals due to the risk of signal reflection and bridging between passive antenna elements, leading to reduced performance and increased size without significant gain.
Innovation Solution
The integrated fan-out (InFO) antenna design features a reflector on a substrate with connecting elements that create a cavity between the patch antenna and the reflector, using a redistribution layer to form an antenna ground and feed structure, which helps in signal propagation while avoiding complex cavity formation within the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solder balls are placed outside the reflector perimeter to bond the package to the PCB, then the package is spaced from the reflector, but signal reflection and bridging between passive antenna elements occur, reducing performance
Solution Approach 1:
A ground plane is introduced as an intermediary element between the patch antenna and the reflector. This ground plane serves as a mediator that provides a controlled impedance path for signals, preventing direct signal reflection from the reflector and avoiding bridging between antenna elements. The ground plane is connected to the reflector through a feed structure, creating an intermediate layer that manages signal flow and improves transmission quality without requiring complex spacing arrangements.
2Reliability
If the package is bonded to the PCB using solder balls surrounding the reflector, then the patch antenna is spaced from the reflector, but the device size increases without significant gain improvement
Solution Approach 1:
The ground plane and feed structure are merged into a unified configuration where the ground plane is directly connected to the reflector through the feed structure. This merging eliminates the need for separate spacing mechanisms like solder balls surrounding the reflector. The combined structure achieves the desired spacing between the patch antenna and reflector while maintaining a compact footprint, improving array gain without increasing device area.
3Reliability
If an air cavity with reflective material is formed in the PCB to create the reflector, then signal reflection is enhanced, but the manufacturing complexity and difficulty of cavity formation increase
Solution Approach 1:
The complex cavity formation process is extracted and replaced by a planar ground plane structure that sits on the surface of the PCB. Instead of creating three-dimensional cavities with reflective material lining, the solution uses a two-dimensional ground plane that provides the necessary signal reflection and isolation functions. This extraction of the cavity formation requirement simplifies manufacturing while maintaining signal reflection efficiency.
4Reliability
If the ground plane area is made larger than the reflector area, then signal isolation and reflection are improved, but the device area increases
Solution Approach 1:
The ground plane dimensions are optimized to be larger than the reflector in specific directions to achieve adequate signal isolation, but not excessively large in all directions. The feed structure connection between the ground plane and reflector is designed with specific geometric parameters that allow effective signal reflection and isolation within a compact area. This parameter optimization ensures signal isolation is improved without unnecessary increase in overall device area.
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 enhances signal reflection and isolation between antenna elements, resulting in improved array gain and reduced size, with the InFO antenna achieving approximately 4 dBi gain compared to 1.5 dBi in devices with solder balls outside the reflector perimeter.
Implementation Method 1
The passive antenna includes a reflector on a printed circuit board (PCB) and a patch antenna on a package. The reflector and patch antenna interact to transmit the signal to external devices.
Implementation Method 2
connecting elements that create a cavity between the patch antenna and the reflector... enhances signal reflection and isolation between antenna elements
Implementation Method 3
using a redistribution layer to form an antenna ground and feed structure, which helps in signal propagation
Data Source
AI summary
A semiconductor device includes an active device. The semiconductor device further includes a plurality of antenna grounds electrically connected to the active device. The semiconductor device further includes a plurality of patch antennas, wherein each patch antenna of the plurality of patch antennas is over a corresponding antenna ground of the plurality of antenna grounds. The semiconductor device further includes a plurality of reflectors, wherein each antenna ground of the plurality of antenna ground is between a corresponding patch antenna of the plurality of patch antennas and a corresponding reflector of the plurality of reflectors. An area of each antenna ground of the plurality of antenna grounds is greater than an area of each reflector of the plurality of reflectors.