A detailed critical review has been made of both solid state power devices and circuit topologies with
emphasis on their application to high frequency electric process heating power supplies operating between
3and 30 MHz.
A number of prototype units have been designed and constructed and their suitability for high frequency
induction heating and dielectric heating applications investigated. Desirable qualities being robustness,
tolerance to load mismatch, ease of design, simplicity and cost of constituent components as compared
with present day valve equipment
The experience gained in these investigations has resulted in the choice of the power MOSFET as the most
appropriate device and Class E amplifier as being the most applicable circuit topology for the generation of
RF power for high frequency electric process heating applications.
A practical and theoretical study has been made of the limitations of the power MOSFET as a high
frequency switching device. The effect of source feedback on the switching speed of T03 packaged
devices has been investigated by the addition of a second source terminal in a specially modified T03
Novel drive circuits have been developed enabling high frequency switching of both power and RF
MOSFETs. These have been employed in inverters operating at 3.3 MHz at power levels up to 600 W and
at frequencies between 7 and 27 MHz at power levels over 100 W, with conversion efficiencies of up to
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy at Loughborough University.