Advanced measurement techniques for VNA accuracy and sensitivity enhancement

S-parameter measurements are advancing on many fronts, ranging from operational frequencies to supported interfaces to extreme loading conditions. The operational frequencies for VNA-based systems continuously extend in frequency range and at present support measurement capability beyond 1.1 THz. The development of RF devices and systems is progressing across many domains that require the support of many interfaces, ranging from the conventional connectorized coaxial and waveguide lines to the on-wafer planar domain. At the same time, RF devices are becoming smaller and using novel materials that impose challenging measurement loading conditions, such as extreme impedances. These challenges imposed on many fronts for S-parameter measurement have an increased need for sensitivity and accuracy, forming the basis of the work outlined in this book.
The first three chapters ddress measurement challenges in coaxial VNA test benches and describe advanced accuracy improvement techniques. Starting with chapter 1, a detailed overview is provided for the S-parameter measurement challenges addressed in this thesis. From here, chapter 2 extends with an introduction to uncertainty sources in connectorized Vector Network Analyzer (VNA) test benches, measurement models, and uncertainty propagation techniques. This forms the basis for chapter 3, which presents advanced methods and strategies for the evaluation of the uncertainty contributions corresponding to the VNA, test-port cables, and coaxial connectors. Moving forward from coaxial VNA measurement systems, the emphasis subsequently is on the primary realization of S-parameter traceability. Chapter 4 describes a method employing a coaxial air-dielectric transmission line for uncertainty evaluation purposes. Here, an improved ripple method is proposed for evaluating uncertainties of a calibrated VNA using a transmission line standard in combination with the Time Domain Signal Extraction (TDSE) algorithm [1]. Chapter 5 describes an advanced model for calibrating transmission line standards using mechanical and material parameters and forms the basis of primary TRL calibration of coaxial VNA systems. The accuracy improvement techniques for coaxial VNA systems are finally extended
to extreme impedance devices. Chapter 6 focuses on measurement of such extreme impedances and introduces the novel interferometer design for ultra-low-noise and broadband measurements, including a novel calibration method for interferometer-based broadband VNAs. With accuracy methods for both matched and high-mismatched environments established, the final part of this thesis aims to expand accurate measurements to the on-wafer domain. Chapter 7 describes our advancements in on-wafer measurements, focusing on RF probing to develop a fully autonomous on-wafer measurement capability. Chapter 8 concludes this thesis with a summary of its main findings and recommendations for future work.