A building block approach to the design of prototype RF systems

This paper presents a description of a building block approach developed to design prototype RF systems at the University of Bath. The approach employed allows systems to be rapidly developed from a library of standard building blocks with a high degree of confidence. Although, developed for RF systems operating in the frequency range 250 MHz to 1800 MHz, the design approach is equally applicable to circuits operating at microwave frequencies. The building blocks implement circuit functions such as general purpose amplifier modules, variable gain amplifier modules and power splitters. The building block circuit layouts are designed and simulated using the Wavemaker microwave design package and the artworks laser printed directly onto acetate film at a 1:1 scale. The circuits are fabricated on one of three standard board sizes using a conventional printed circuit technique on Duroid material. The building blocks are measured using an HP8510 Vector Network Analyser, and have shown good agreement with the simulations provided by the Wavemaker package. The use of a microwave CAD package with a library of building blocks enables prototype RF systems to be designed quickly by integrating a number of building block circuit layouts together with relatively low risk. Prototype systems for a general purpose amplifier chain and an isolation module have been successfully designed using this technique