Interposing PCB Layout for Shorter 5G Antenna Feed Paths
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Solution Overview
Problem
Existing wireless communication systems face challenges in reducing the burden on radio unit (RU) boards and minimizing transmission line lengths to improve antenna performance, particularly in high-frequency bands like the mmWave band.
Innovation Solution
The introduction of an interposing board that separates RF lines from the main PCB, providing vertical connections between antenna elements and RFICs, using grid arrays to minimize transmission losses and optimize feeding performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If antenna elements are integrated directly on the RU board, then device complexity is reduced, but transmission line length increases causing signal loss
Solution Approach 1:
The system is divided into separate functional modules: antenna elements on a first PCB, RFICs on a second PCB, and an interposing board with feeding ports. This segmentation allows optimization of each module independently while reducing overall transmission loss through minimized interconnect lengths.
Solution Approach 2:
An interposing board is introduced as a mediator between the antenna elements and RFICs. This intermediary board provides optimized feeding ports and transmission lines that minimize signal loss while maintaining electrical connectivity, acting as a buffer that resolves the conflict between integration and performance.
2Loss of energy
If transmission line length is minimized on the RU board, then signal transmission performance improves, but the RU board becomes more complex
Solution Approach 1:
The solution moves from a two-dimensional planar layout to a three-dimensional stacked configuration with multiple PCB layers and vertical interconnections. This dimensional change allows transmission lines to be routed through multiple layers and via holes, minimizing surface transmission length while organizing complexity vertically rather than horizontally.
Solution Approach 2:
The interposing board serves as a mediator that handles the complex routing and connection logic, allowing the main RU board to maintain a simpler structure. The intermediary absorbs the complexity of minimized transmission line routing while providing clean interfaces to both antenna elements and RFICs.
3Reliability
If feeding ports are positioned to match antenna element ports, then feeding performance is optimized, but manufacturing precision requirements increase
Solution Approach 1:
The interposing board is designed with feeding ports pre-positioned to match antenna element port locations. This preliminary positioning action is captured in the PCB layout and manufacturing process, ensuring accurate alignment before final assembly. The board is manufactured with precise port locations built-in, eliminating the need for post-assembly adjustment.
Solution Approach 2:
The interposing board creates a copied or replicated interface pattern that matches the antenna element port arrangement. By copying the port positions from the antenna array design into the interposing board layout, the system ensures perfect alignment without requiring high-precision manual positioning during assembly, as the geometric relationship is preserved through the copying process.
Data Source
AI summary
A 5th Generation (5G) or pre-5G communication system for supporting a data transfer rate higher than that of a post-4th Generation (4G) communication system such as Long Term Evolution (LTE) is provided. The radio unit (RU) device includes a first printed circuit board (PCB) on which a plurality of antenna elements are disposed, a second PCB on which a radio frequency integrated circuit (RFIC) is disposed, and a third PCB configured to electrically connect each of the plurality of antenna elements and the RFIC between the first PCB and the second PCB, a first surface of the third PCB is coupled to a first surface of the first PCB through a grid array, and positions of feeding ports on the first surface of the third PCB correspond to positions in which ports of the plurality of antenna elements are disposed on a second surface opposite the first surface of the first PCB.