Matching Networks Etched on High Dielectric Constant Substrates for Power MESFET Modeling

In this paper are the results of simulation of matching networks for power MESFET´s are presented. The technique of modeling is based on substitution of coupled microstrip by equivalent single microstrip placed inside magnet field webs. The designated power MESFET has L-C-L type matching networks. The lumped capacitors were realized as parallel plate capacitors on 0.3 mm thick ceramic substrates, which have high dielectric constant. The inductors were approximated by bond wires. The distance between microstrip lines on ceramics is equal 40 microns that causes the strong coupling between them. Modeling of scheme with coupling lines has hard mathematic problems. This problem is solved by replacement of the coupled lines by the equivalent single lines. The wave impedance and slowness factor have been defined for a single micro-strip line located between magnetic walls. This approach allows us to take into account a coupling of microstrip lines at designing a matching networks of power transistor