Highly Integrated Microwave Vector Network Analysis Circuits and Systems for Instrumentation and Sensing Applications

Abstract

This thesis addresses the topic of highly integrated vector network analysis. Due to its significant contribution to technological advances in the past and its presently high potential regarding instrumentation and biomedical sensing applications, the technique of network analysis plays a key role in microwave and wireless engineering. However, the application of network analyzers is frequently limited due to the size, weight and cost of the instruments. For this reason, the potential and feasibility of the VNA-on-chip is evaluated. Therefore, theoretical and practical studies were performed by means of narrow-band microwave reflectometers with different degrees of integration. After a successful proof of concept, a chipset dedicated to a highly integrated 4-32 GHz 2-port vector network analyzer is developed in silicon germanium (SiGe) technology. The chipset can be utilized for the implementation of a heterodyne network analyzer and features a stimulus signal generator with integrated switch and a four-channel receiver chip. In a further step, a fully integrated RF frontend is demonstrated, including on-chip directive elements. In combination with a modular hardware demonstrator, the assembly serves as a miniaturized 2-port vector network analyzer from 4 GHz to 32 GHz. The measured 2 x 2 S-matrices show an excellent agreement with the results obtained by commercial measurement equipment. The measurements are highly repeatable and the drift over time is negligible. Furthermore, highly integrated network analyzers were applied to biomedical scenarios. For this purpose, a reflection based analyzer with external probe as well as a transmission based one with an on-chip sensor are presented and compared to an alternative sensing system.