Two-stage ultrawide-band 5-W power amplifier using SiC MESFET

This paper describes a two-stage 5-W broad-band amplifier covering the frequency range from 10 MHz to 2.4 GHz. An SiC MESFET is used as the power stage. A large-signal table-based model has been developed and verified for the SiC device by comparison with measurements. A novel broad-band choke structure was developed to obtain high dc isolation and low RF loss over the full bandwidth. No impedance transformer was used at all. Broad-band input and output matching networks and shunt feedback topology were introduced to fulfill the bandwidth requirements. Typical values of 22-dB power gain, 37-dBm output power, 28% power-added efficiency, and 47-dBm third-order intercept points have been achieved in a two-stage design using a GaAs MESFET as driver stage. All power and linearity results were obtained over the whole frequency band. The design procedure is given in detail and the results are being discussed and compared with simulations.