Design of Broadband Microwave FET-Amplifiers

A new design method for broadband microwave FET-amplifiers is outlined. The design procedure utilizes the measured S-parameters of the FET and neither a new synthesis method nor a new transfer function approximation is required. Instead the equalizing networks are developed from conventional matched Butterworth or Chebyshev ¿go/4-transformers using network transformations. The final equalizers are composed of cascaded commensurate transmission lines which are slightly shorter than ¿go/8. The theoretical and experimental results of 2-6 GHz and 2-8 GHz single-stage FET-amplifiers are given showing that the proposed method - even without a correcting optimization - gives good amplifier performance. Gains of 10.1 ± 0.6 dB and 8.4 ± 0.6 dB were measured, respectively, in bands 2.0 - 6.0 GHz and 2.0 - 7.9 GHz with associated noise figures 3.1 ± 0.1 dB and 3.8 ± 1.1 dB.