Conventional line-frequency/DC power supplies and RF power supplies are two main types of power supply equipment in power electronics. Conventional power supplies are characterised by low frequency, constant voltage and constant current, and conductive power transfer, and are widely used in consumer and basic industrial applications. RF power supplies, offering high frequency, electromagnetic field coupling, and plasma excitation, are key components in high-end manufacturing sectors such as semiconductors, photovoltaics, and vacuum coating. In this paper, the authors from Watsean, a Chinese RF power supply manufacturer, present a comparative analysis of the two types based on their operating principles, electrical characteristics, system architecture, control strategies, and application scenarios, elucidating their fundamental differences and technical boundaries to provide guidance for engineering selection and system design.

I. Introduction
In power electronics and industrial equipment systems, the power supply is a fundamental component that determines equipment performance and process realisation. Traditional power supplies (line-frequency AC, linear DC, and switched-mode DC) aim to provide a stable energy supply, offering high versatility and low cost. RF power supplies are high-frequency specialised power sources that deliver power in the kHz to GHz range, enabling non-contact energy coupling and plasma excitation, making them indispensable in high-end manufacturing.

Currently, the technical boundaries between the two remain unclear in engineering applications, leading to difficulties in selection. This paper provides a comparison of RF power supplies and conventional power supplies from multiple perspectives, offering a theoretical basis for scientific research and engineering practice.

II. Working Principles and Basic Characteristics
2.1 Conventional Power Supplies
Conventional power supplies primarily include line-frequency AC and DC power supplies, outputting 50/60 Hz low-frequency AC or constant DC. The energy conversion path is: AC line input → rectification and filtering → voltage transformation → voltage regulation/constant current output. Energy is transmitted directly via conductors through ohmic conduction, making these power supplies suitable for conventional resistive, inductive, and capacitive loads.

2.2 RF Power Supplies

RF power supplies generate industrial-grade high-frequency sinusoidal or pulsed signals at frequencies such as 13.56 MHz, 27.12 MHz, and 40.68 MHz. The typical structure is: front-end rectification and power factor correction (PFC) → high-frequency inversion and power amplification → impedance matching network → load. It transmits energy via high-frequency electromagnetic field coupling and can excite plasma in a vacuum or insulating medium, no longer adhering to simple Ohm’s law.

III. Comparison of Core Technical Specifications
Operating Frequency
Conventional power supplies: 0 Hz (DC) or 50/60 Hz (line frequency); RF power supplies: in the kHz to GHz range, far exceeding line frequency.

Output Waveform
Conventional power supplies: DC or standard low-frequency sine waves, with low ripple; RF power supplies: high-frequency continuous waves or pulsed waves, emphasising spectral purity and phase stability.

Energy Transfer Method
Conventional power supplies: conductive transmission, reliant on conductive circuits; RF power supplies: electromagnetic field coupling, capable of contactless operation and delivering power in vacuum or insulating environments.

Impedance and Matching
Conventional power supplies: insensitive to impedance variations, no matching network required; RF power supplies: load impedance fluctuates significantly, necessitating the use of an automatic impedance matcher to reduce the standing wave ratio and suppress power reflection.

IV. System Architecture and Control Strategies
4.1 System Architecture
Conventional power supplies consist of rectification, filtering, voltage transformation, and voltage regulation circuits; they feature a simple structure and use standard components. RF power supplies comprise units such as signal generation, power amplification, directional coupling, automatic matching, and high-frequency protection; they impose extremely high demands on shielding, heat dissipation, and EMI suppression.

4.2 Control and Protection
Conventional power supplies aim to stabilise voltage and current, with protection primarily focused on overvoltage, overcurrent, and overheating. RF power supplies control output power, frequency, phase, and matching status, and incorporate high-frequency-specific mechanisms such as standing wave ratio protection and reflected power protection.

V. Differences in Application Scenarios
5.1 Conventional power supplies are used in household appliances, consumer electronics, lighting, conventional motor drives, and industrial control equipment, emphasising versatility and low cost.

5.2 RF power supplies are primarily used in:

Semiconductor lithography, etching, PVD/CVD coating, and plasma cleaning;

Thin-film preparation for photovoltaics and display panels;

Surface modification of materials, plastic welding, and medical RF ablation;

Radar and communication transmitters.

In vacuum, insulating, and non-conductive load scenarios, standard power supplies cannot serve as a substitute.

VI. Conclusion

Conventional power supplies are basic, general-purpose power supplies that primarily utilise DC or low-frequency AC power and conductive power transfer, with a focus on stability and low cost.

Radio-frequency (RF) power supplies are specialised power sources for high-end processes, centered on high-frequency electromagnetic field coupling, and enable advanced manufacturing and specialised applications.

The two types differ fundamentally in terms of frequency, operating principles, structure, control, and application, and are not interchangeable.

With the development of high-end manufacturing, RF power supplies will evolve towards all-solid-state, digital designs, wide-bandgap devices, and high power density, forming a comprehensive modern power electronics system alongside conventional power supplies.