Embedded Wilkinson PCB Divider Using Resistive Foil for Low-Loss Isolation

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Solution Overview

Problem

Conventional Wilkinson power dividers have a large footprint and high loss in high-frequency applications, making them unsuitable for compact RF communication systems.

Innovation Solution

A Wilkinson power divider is embedded within a multi-layer PCB using embedded coplanar waveguides and a resistive foil, with non-circular traces and a resistive foil resistance of 25-200 ohms per square, to achieve high isolation and low loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional Wilkinson power dividers are used, then isolation between output ports is maintained, but device footprint becomes large and loss increases

Engineering Contradiction:

Improvepower lossVSAvoiddevice footprint

Core Design Contradiction:

Loss of energyVSArea of stationary object

Solution Approach 1:

The Wilkinson power divider is transitioned from a planar microstrip implementation to a three-dimensional embedded structure within multi-layer PCB. The power divider is positioned between ground planes on different layers, utilizing the vertical dimension to achieve compactness while maintaining electrical performance. This dimensional transition allows the device to occupy minimal footprint area on the PCB surface while providing adequate isolation and low loss through proper electromagnetic field confinement.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The Wilkinson power divider is nested within the multi-layer PCB structure, with the power divider circuit embedded between internal ground planes. The isolation resistor is positioned in the same layer as the power divider circuit, and the entire assembly is surrounded by ground planes on adjacent layers, creating a nested configuration that maximizes space utilization and minimizes external interference.

Inventive Principle:

Principle #7Nested doll (Nesting)

2Device complexity

If conventional Wilkinson power dividers are used, then port matching is maintained, but device complexity and footprint increase

Engineering Contradiction:

Improvestructure complexityVSAvoiddevice footprint

Core Design Contradiction:

Device complexityVSArea of stationary object

Solution Approach 1:

The Wilkinson power divider is merged with the multi-layer PCB structure itself, utilizing the PCB's internal ground planes and signal layers to form the power divider circuit. The isolation resistor is integrated into the same layer as the power divider traces, and the entire assembly is incorporated within the existing PCB layer stack-up, eliminating the need for separate discrete components and reducing overall structural complexity.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If embedded coplanar waveguides are used, then isolation is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improveisolation performanceVSAvoidtrace fabrication precision

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The design utilizes standard PCB fabrication parameters and materials, with trace widths, spacing, and layer distances optimized for the specific PCB stack-up. The isolation resistor is implemented with a resistance value and physical dimensions that achieve the required isolation performance while being compatible with standard resistor manufacturing tolerances. The embedded coplanar waveguide dimensions are selected to provide robust isolation performance that is not overly sensitive to minor fabrication variations.

Inventive Principle:

Principle #35Parameter changes

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

The embedded design provides high isolation with low loss and a compact footprint, suitable for high-frequency applications such as satellite communications and 5G/6G devices.

Implementation Method 1

a resistive foil as its isolation resistor. The resistive foil may have an ohms per square (OPS) resistance in the range of 25-200 OPS

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

The embedded Wilkinson power dividers described herein provide high isolation with low loss using a compact design with a small device footprint

Methodology Applied

Scientific EffectElectromagnetic wave propagation: Waveguide

Data Source

PatentUS20250316878A1Embedded wilkinson power divider with resistive foil within multi-layer printed circuit board

Publication Date: 2025.10.09 SANMINA CORP

AI summary

A Wilkinson power divider is embedded in a multi-layer printed circuit board (PCB). In one example, the power divider is configured as an embedded coplanar waveguide with ground (CPWG) device. In another example, the embedded Wilkinson power divider is configured using striplines. In both examples, a resistive foil is used as the isolation resistor of the Wilkinson power divider. In some examples, the two arms of the Wilkinson power divider have semi-oval shapes. The device may be configured to provide a wide impedance bandwidth (e.g., in the range of 24-31 GHz) with minimal return loss and insertion loss. Cascaded configurations are also described herein.