Multi-Path Power Amplifier Capacitor for Coupling Compensation

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Solution Overview

Problem

The increasing integration and miniaturization of power amplifier components lead to reduced isolation between components, resulting in parasitic coupling that degrades efficiency and performance, particularly in terms of inductive coupling between wires/leads of transistors.

Innovation Solution

Incorporating a planar capacitor between amplifier paths to compensate for parasitic or inductive coupling, using configurations such as microstrip or parallel plate capacitors on the substrate or within the packaged semiconductor device to maintain isolation and improve performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If power amplifier components are miniaturized and integrated to reduce size, then device compactness is improved, but isolation between components deteriorates leading to increased parasitic coupling

Engineering Contradiction:
Improvedevice sizeVSAvoidparasitic coupling
Core Design Contradiction:
Volume of moving objectVSObject-affected harmful factors

Solution Approach 1:

A capacitor is introduced as an intermediary component between the amplifier paths to compensate for the parasitic coupling. The capacitor is coupled between the input terminals or output terminals of the amplifiers, acting as a mediator to cancel out the inductive coupling effects caused by miniaturization and increased integration density.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the electrical parameters of the system by adding a capacitor with specific capacitance value to alter the coupling characteristics. By adjusting the capacitor value, the parasitic inductive coupling can be compensated, transforming the harmful coupling effect into a beneficial cancellation effect while maintaining the compact device structure.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If component isolation is reduced to achieve higher integration, then device complexity is reduced, but performance degradation occurs due to increased coupling

Engineering Contradiction:
Improveisolation structure complexityVSAvoidamplifier performance
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The capacitor serves as a simple intermediary element that compensates for coupling effects without requiring complex isolation structures. This approach maintains device simplicity while improving reliability by addressing the coupling problem through a single compensating component rather than complex physical isolation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful parasitic coupling effect into a beneficial compensation mechanism. By intentionally adding a capacitor that creates an opposing reactive effect, the harmful inductive coupling is transformed into a controlled and compensated interaction, improving amplifier performance without requiring increased isolation.

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

3Object-affected harmful factors

If capacitor compensation is added to compensate for coupling, then isolation is improved, but device complexity increases

Engineering Contradiction:
Improvecoupling compensationVSAvoidcircuit configuration
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The capacitor is implemented as a straightforward intermediary component with simple terminal connections, either between input terminals or output terminals of the amplifiers. This minimalistic implementation provides effective coupling compensation while adding only a single component to the circuit, avoiding significant increases in device complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 capacitor configurations provide improved isolation, enhancing efficiency and peak power performance by mitigating electromagnetic interference, with potential improvements ranging from 2 to 10 decibels with minimal additional cost or development.

Implementation Method 1

the impact of the coupling is most pronounced in terms of an inductive coupling (e.g., mutual inductance) involving wires/leads of components (e.g., transistors)

Methodology Applied
Scientific EffectInductive coupling: Electromagnetic Induction

Implementation Method 2

a capacitor having a value that compensates for the coupling between the wires/leads of the transistors

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP4579743A1Multiple-path power amplifier with capacitor for compensating for a coupling between amplifier paths
Publication Date: 2025.07.02 NXP USA INC
  • EP4579743A1 patent drawingFigure 1
  • EP4579743A1 patent drawingFigure 2
  • EP4579743A1 patent drawingFigure 3

AI summary

Aspects of this disclosure are directed to various circuit topologies for mitigating coupling. In some embodiments, an amplifier circuit is provided that includes a first amplifier path, a second amplifier path, and a capacitor. The first amplifier path may include a first input, a first transistor, and a first wire coupled between the first input and a first terminal of the first transistor. The second amplifier path may include a second input, a second transistor, and a second wire coupled between the second input and a first terminal of the second transistor. The capacitor may include a first terminal coupled to the first input and a second terminal coupled to the second input. Under such an arrangement, the capacitor may be configured to compensate for a coupling between the first wire and the second wire. Other embodiments are disclosed.