Monolithische GaAs FET- und HBT-Oszillatoren mit verbesserter Transistormodellierung

Abstract

This thesis treats analysis and optimization of monolithic integrated oscillators (MMIC–VCO) on GaAs. The first part describes small–signal modelling of GaAs field–effect–transistors (FET) and hetero–bipolar–transistors (HBT). For HBTs, a new algorithm is presented, which allows reliable extraction of the small–signal equivalent–circuit elements. It was successfully employed with SiGe and InP HBTs as well. Furthermore, the low–frequency noise of GaAs HBTs is investigated and an extraction routine for the relevant noise sources is developed. In a second step, these results are applied to the reflection–type oscillator, a well–known concept in microwave circuits. The relation between loop–gain, loaded Q and phase noise is derived. This leads to a new design strategy, which allows maximizing the loaded Q. As an example, MMIC–VCOs at 38 GHz and 77 GHz are realized, which achieve best–in–class phase–noise values.