Designing distributed amplifiers for prescribed gain slope

A distributed amplifier can produce a positive gain slope over very wide frequency ranges and still maintain excellent input and output match. It is equally capable of flat or negative gain/frequency characteristics and is much more tolerant to process variations than the reactively matched alternative. A simple description is given of the behaviour of the distributed amplifier structure, concentrating on those aspects that are relevant to the gain slope and which allow design for positive, flat and negative gain slopes. Three different 6-18 GHz MMIC amplifiers are described, one for each category, that were made at an MMIC processing facility now installed at Philips Microwave (Hazel Grove). The cascading of six of the MMIC amplifiers to produce a high gain module with an exceptionally flat response (32+/-0.5 dB) is also described. Simulated and practical results are presented