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Code: EP115

Description

This video lecture illustrates typical packaging of MIC devices and the internal connections, and examines the equivalent circuit and its impact on performance. Designs to DC bias PIN diodes by presenting high RF impedance, and the use and performance of DC breaks are also described. Measurements include S-parameters, and a video sequence shows laboratory measurements using a scalar network analyser, of a microstrip parallel line filter etched on RT/duroid. Packaging involves coaxial-to-microstrip transitions illustrated by pictures. The theory of measurement characteristics is presented, including excess phase arising at field perturbations at the coax-to-microstrip boundary, and multiple reflections between the transition and the device under test. The effect of packaging enclosures on performance shows that small enclosures significantly increase the capacitance per unit length and therefore reduce Z0. Also considered are techniques of avoiding the formation of waveguide mode in the package by the use of lossy material and metal posts within the enclosure. The lecture concludes by considering monolithic microwave integrated circuits (MMICs), realised in GaAs, which can achieve high performance and low loss by having low losses, low noise and good matching between transistors.