Measurement instruments are essential tools for engineers to be able to test and verify the performance of electrical circuits and systems before integration into a product. Development times of products can be shortened through rapid prototyping using models extracted from accurate measurements. This thesis deals with the development of measurement instruments and methods for characterization of nonlinear microwave devices.
Nonlinearities in microwave circuits can for example arise through intentional overdrive for high efficiency operation or due to non-idealities in components. Modern cellular standards such as 4G, and the upcoming 5G standard, use communication signals with wide bandwidths to allow for higher data throughput in the cellular networks. Therefore, distortion due to nonlinearities is of increasing importance to study using wideband signals. As such, a wideband nonlinear measurement setup has been designed and verified in this thesis.
Designing high performance circuits for next generation wireless applications also requires the utilization of semiconductors with better material properties compared to silicon, such as gallium nitride (GaN). With GaN, higher output powers at higher frequencies are possible to obtain, allowing for e.g. higher data rates at longer distances between the base station and cell phone. However, GaN suffers from performance-degrading effects such as electron trapping, which is a result of defects in the GaN material. In order to understand these effects, and to be able to optimize the GaN material, there is a need for measurements which can capture trapping phenomena in a methodical way. This thesis also deals with characterization of such phenomena.
The measurement instruments and methods developed in this thesis can aid in the understanding of nonlinear phenomena, enabling the design of high performance circuits for next generation wireless applications.