Novel semi-reactively-matched multistage broadband power amplifier architecture for monolithic ICs in GaN technology

This paper reports on a novel broadband amplifier architecture suitable for wide bandwidth applications such as electronic warfare systems. The proposed topology comprises a distributed active power splitter to function as a driver stage for a reactively-matched power amplifier. As a result, a purely resistive interstage impedance is obtained and therefore the proposed architecture allows wider bandwidth operation as compared to the conventional reactively-matched multistage topology. Due to the traveling wave amplifier character of the driver stage, the presented novel amplifier topology is named semi-reactively-matched amplifier. A 6GHz to 20GHz dualstage high power amplifier MMIC is designed and realized in order to demonstrate the capabilities of the new concept. The MMIC is based on a 0.25μm gate length AlGaN/GaN HEMT microstrip transmission line technology. It shows a measured small-signal gain of (18 ± 4)dB over the entire frequency range. The saturated output power is higher than 4.5W at 20GHz in continuous wave operation.