TABLE OF CONTENTS Previous chapters presented fundamental concepts describing mixed-mode s-parameters along with differential amplifiers, transmission lines, and power splitter/combiner applications. This chapter will present a differential filter, a directional coupler, and a differential isolator as example applications. These application examples demonstrate mixed-mode s-parameter matrix operations and parameter extraction techniques. This chapter reviews the indefinite matrix operation, a unique redefinition of the common (ground) port and applies it to mixed-mode circuits. The chapter begins with a brief review of the small-signal network matrix representations as background for circuit linear transfer models and behavioral impedance models. This chapter ends with mixed-mode analysis of a differential band-pass filter, a dual directional coupler, and a differential isolator.
Any passive or active linear time-invariant network can be represented with a set of terminal voltage and current values across a frequency range of interest. The simplest of networks is the two-terminal network shown in Figure 6.1(a), with the voltage potential v 1 across the two terminals and the current i 1 into terminal 1. For this simple two-terminal network, there will be an equal amplitude current i 1 (with a different phase-) at terminal 2 (given a circuit in steady-state with no other ports such as internally grounded ports). The current, i 1 is a function of the network impedance and the voltage v 1
