28.1 Introduction

Electronic circuits operating at high frequency present some unique challenges to proper characterization. At high frequencies the wavelengths of operation become similar in dimension to the physical properties of circuit elements. This results in circuit performance that is distributed in nature. Rather than describing the voltage and current at a specific circuit node it is more appropriate to describe how waves in a transmission medium respond to a component in their path. Network analyzers are a class of instruments that have been developed to characterize radio-frequency (rf) components accurately and efficiently as a function of frequency. Network analysis is the process of creating a data model of the transfer and/or impedance characteristics of a linear network through stimulus-response testing over the frequency range of interest. At frequencies above 1 MHz, lumped elements actually become circuits consisting of the basic elements plus parasitics like stray capacitance, lead inductance, and unknown absorptive losses. Since parasitics depend on the individual device and its construction they are almost impossible to predict. Above 1 GHz component geometries are comparable to a signal wavelength, intensifying the variance in circuit behavior due to device construction. Network analysis is generally limited to the definition of linear networks. Since linearity constrains networks stimulated by a sine wave to produce a sine-wave output, sine-wave testing is an ideal method for characterizing magnitude and phase response as a function of frequency. This chapter discusses the key parameters used to characterize rf...