RF and Microwave Circuit Design

3Fabrication Processes for RF and Microwave Circuits

3.1 Introduction

As frequencies increase into the high RF and microwave regions, the materials and fabrication technologies used to manufacture planar circuits assume greater significance. Good circuit design at these high frequencies is very much dependent on the selection of appropriate materials and fabrication processes, and it is essential that the circuit designer should have an appreciation of the properties and limitations of the available circuit materials and associated manufacturing processes. This chapter introduces the main fabrication processes and materials that are available, and provides an indication of their relative merits.

The chapter commences with a review of the parameters used to describe the performance of high-frequency circuit materials, and then expands the discussion to list the essential requirements for materials for RF and microwave circuit applications.

The choice of a fabrication process for a particular circuit application is of critical importance, and has a significant effect on the electrical circuit design. Recent developments in materials for high-frequency applications offer the circuit designer a wide choice of circuit structures. One particularly useful development, which provides the designer with significantly greater flexibility, is that of relatively low-cost multilayer circuit processes. Once the sole province of the monolithic circuit designer, multilayer techniques using ...