The Evolution of Very High Frequency Switch Mode Power Circuits


Event Speaker: 

Arnold Knott

Event Location: 


Event Date/Time: 

Tuesday, November 6, 2012 - 10:00am

(Hosted by Prof. David Perreault)


Switch-mode power circuits evolved through the communication engineering discipline. The generated knowledge within this field got applied in power electronics and developed a field on its own. The talk will review the radio frequency amplifier classes and how they got reused in power electronics. As a niche in power electronics the specialties of switch-mode audio power amplifiers (Class-D) are revisited. The combination of oscillators and power circuits are described and the various variants of those so called self-oscillating power circuits are shown.  Within recent years the original principles from the communication engineering (Class-E, got combined with modern power electronics, striving for low volume, weight and price. The latest research results from the Technical University of Denmark in this field are presented: application of self-osciallting principles to Class-E-based converters, choice of power semiconductors, and development of light weight, low-profile inductors. The presented demonstrators include a 120 MHz, 9 W LED driver  with an efficiency of 89 % at continuous operation. Finally advantages and the remaining challenges of very high frequency power circuits are discussed.


Arnold Knott received the Diplom-Ingenieur (FH) degree from the University of Applied Sciences in Deggendorf, Germany, in 2004. From 2004 until 2009 he has been working with Harman/Becker Automotive Systems GmbH in Germany and USA, designing switch-mode audio power amplifiers and power supplies for automotive applications. In 2007 he joined the Technical University of Denmark for working on a research project under the title "‘Improvement of out-of-band Behaviour in Switch-Mode Amplifiers and Power Supplies by their Modulation Topology". He got his Ph.D degree in 2010 and since then he is assistant professor at the Technical University of Denmark. His interests include switch-mode audio power amplifiers (Class-D), power supplies, active and passive components, acoustics, radio frequency electronics, electromagnetic compatibility and communication systems.