PCB RF Transition Structure for Resonance-Free Connector Coupling

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Solution Overview

Problem

Conventional printed circuit board (PCB) connectivity for radio frequency (RF) connectors suffers from signal resonance modes, leading to insertion loss and return loss notches, especially in the millimeter waveband, causing system failures and bandwidth bottlenecks in high-speed telecommunications.

Innovation Solution

A PCB design with a RF signal transition structure featuring a blind via and a ground cage structure, along with a reduced number of bends in the RF signal path, is implemented to minimize impedance discontinuities and resonance modes, using WSMP, G3PO, or SMPS surface mount RF connectors for improved RF signal coupling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If conventional GPO or GPPO connectors are surface-mounted or edge-mounted on PCB, then connector assembly is achieved, but signal resonance modes are excited causing insertion loss and return loss notches

Engineering Contradiction:

Improveconnector assemblyVSAvoidsignal transmission quality

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent extracts the harmful air gap between the connector body and PCB cut-out, eliminating the source of resonance. By removing this problematic space and directly coupling the connector to the PCB, the design prevents excitation of signal resonance modes while maintaining ease of assembly.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent transitions from conventional surface-mount or edge-mount configurations to a embedded dimension where the connector body is directly integrated into the PCB structure. This dimensional change eliminates the air gap interface and creates a seamless transition for RF signals, preventing resonance without complicating the manufacturing process.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If air gap is provided between connector body and PCB cut-out, then connector assembly is simplified, but resonance notches occur in the frequency band

Engineering Contradiction:

Improveconnector assemblyVSAvoidresonance notches

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent converts the problematic air gap into a beneficial direct coupling structure. By eliminating the air gap that causes resonance, the design transforms the assembly approach to achieve both ease of manufacture and immunity from resonance notches, turning a harmful factor into a beneficial seamless interface.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of operation

If multiple bends are included in connector pin, then connector connectivity is achieved, but impedance discontinuities increase causing resonance

Engineering Contradiction:

Improveconnector connectivityVSAvoidimpedance continuity

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

Instead of using multiple bent pins to achieve connectivity, the patent inverts the approach by using a straight pin configuration with the connector body directly mounted on the PCB. This inversion eliminates the bends that cause impedance discontinuities while maintaining full connector connectivity through the direct-coupled structure.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11791527B2Printed circuit boards and methods for manufacturing thereof for RF connectivity between electro-optic phase modulator and digital signal processor

Publication Date: 2023.10.17 CIENA CORP

AI summary

A Printed Circuit Board (PCB) and methods for manufacturing the PCB board are provided. The PCB includes a Radio Frequency (RF) signal transition at a RF signal pad. Multiple conductive layers other than a conductive signal layer of the PCB and conductive portions of the conductive signal layer not in electrical contact with a RF signal transmission trace have common ground connections forming a ground cage structure within the PCB around the RF signal pad and RF the signal transmission trace.