Overview

RF and microwave design is performed primarily in the frequency domain, probably because the original sources were continuous wave (CW) devices, and different signals were separated by their frequencies. Time-domain analysis of RF and microwave components is becoming more important, especially for communication systems employing extremely complex modulation schemes, but the majority of work is still undertaken in the frequency domain. The design techniques described within this chapter will concentrate on the frequency domain.

The design of MMICs is essentially the same as that for most microwave components: one or more signals must be coupled onto the chip efficiently, then functions are performed on the signals, after which they are then coupled out of the chip and back into the system. Later sections will show that the efficient coupling of signal power requires that the impedance of the signal source match that of the chip. In fact, to pass the signal efficiently through the whole chip, the impedances of the transmission lines, the active devices, and the system it sits in must all be matched. Separation of RF signals from dc bias requires impedance mismatching, and filtering of different RF signals requires impedance changes versus frequency. Thus, MMIC design is founded on impedance matching and control across the frequency range of interest.

This chapter begins with these basis principles of impedance matching and shows how impedances may be plotted and transformed using the Smith chart. The chapter goes on to discuss the design of passive elements, such as couplers...