Planar PCB Power Transformer in High-Frequency Amplifiers for Fanless Cooling

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Solution Overview

Problem

High-frequency amplifiers used for plasma excitation face challenges in heat management, particularly during continuous wave operation, as they often require fans to dissipate heat generated by reflected power, which can lead to inefficiencies and increased costs.

Innovation Solution

A high-frequency amplifier arrangement utilizing two LDMOS transistors with a power transformer, where the primary and secondary windings are designed as planar conductor tracks on different layers of a multi-layer circuit board, allowing for efficient heat dissipation and optimized impedance matching to minimize power loss through harmonic termination, eliminating the need for fans.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If conventional amplifier arrangements are used for plasma excitation, then power output can be achieved, but heat generation increases requiring fan cooling

Engineering Contradiction:
Improveoutput powerVSAvoidheat generation
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The patent converts the harmful reflected power that would normally be dissipated as heat into useful plasma excitation energy. By injecting the reflected power back into the plasma load through the feedback network, the system transforms waste energy into beneficial electromagnetic energy for plasma generation, thereby reducing heat generation in the amplifier while maintaining output power capability

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

Solution Approach 2:

The patent implements a feedback mechanism where a portion of the output signal is fed back to the input through a feedback network. This feedback allows the amplifier to maintain stable operation and efficiently handle reflected power by adjusting the input signal accordingly, preventing excessive heat generation while maintaining the required output power for plasma excitation

Inventive Principle:
Principle #23Feedback

2Temperature

If fans are added for heat dissipation, then temperature control improves, but device complexity and cost increase

Engineering Contradiction:
Improveheat dissipationVSAvoidcooling system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent enables the amplifier system to self-regulate its thermal management through the feedback mechanism. By automatically injecting reflected power back into the plasma load, the system self-adjusts its energy distribution to minimize heat generation in the amplifier components, eliminating the need for external active cooling systems like fans and thereby reducing device complexity

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The reflected power that would normally require active cooling to manage is instead converted into useful plasma excitation energy. This transformation reduces the thermal load on the amplifier components to such an extent that passive cooling or natural convection suffices, eliminating the need for complex fan-based cooling systems

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

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 solution enables efficient heat dissipation and reduced power loss, achieving high-frequency plasma excitation without the need for fans, thereby improving operational efficiency and reducing manufacturing costs while maintaining high output powers and frequencies.

Implementation Method 1

a power transformer whose primary winding is connected to the drain terminals of the transistors

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

a capacitance which is connected in parallel to the primary winding of the power transformer, and a further capacitance which is connected in parallel to the secondary winding of the power transformer

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 3

the transistors are designed as LDMOS transistors

Methodology Applied
Scientific EffectField effect transistor operation: Diode

Data Source

PatentEP3579409B1High-frequency amplifier arrangement
Publication Date: 2023.11.08 TRUMPF PATENTABTEILUNG
  • EP3579409B1 patent drawingFigure 1
  • EP3579409B1 patent drawingFigure 2~3
  • EP3579409B1 patent drawingFigure 4

AI summary

A high-frequency amplifier arrangement (1) suitable for generating output powers ≥ 1kW at frequencies ≥ 2MHz for plasma excitation, comprising: a. two transistors (S1, S2) which are each connected at their source and emitter terminals to a ground connection point (5), wherein the transistors (S1, S2) are of the same design and are arranged on a multilayer printed circuit board (2), b. a power transformer (7) whose primary winding (6) is connected to the drain and emitter terminals of the transistors (S1, S2), c. the primary winding (6) and the secondary winding (4) of the power transformer (7) are each designed as planar conductors which are arranged in different upper layers (61, 62) of the multilayer printed circuit board (2).