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This letters presents a new wideband power amplifier approach to achieve high performance of wideband frequency operation from low frequency such as 80-2100 MHz for two-way radio applications. The approach is referring to distributed power amplifier with phase adjustment of the gate line network to balance with drain line network (specifically with drain line tapering). Experimental of the prototype level with gallium nitride high-electron-mobility-transistor demonstrated output power of 41 dBm, flat gain at 12 dB, and bandwidth covering 80 MHz to 2.1 GHz with power added efficiency of 45% under 28 V drain bias. According to the author's knowledge, this work has illustrated a significant enhancement in efficiency over the conventional topology, low cost implementation, and offers wideband operation for public safety applications. [ABSTRACT FROM AUTHOR]

The self-biasing circuit through a feedback resistor is applied to a gallium nitride (GaN) distributed power amplifier (PA) monolithic microwave circuit (MMIC). The self-biasing circuit is a useful scheme for biasing depletion-mode compound semiconductor devices with a negative gate bias voltage, and is widely used for common source amplifiers. However, the self-biasing circuit is rarely used for PAs, because the large DC power dissipation of the feedback resistor results in the degradation of output power and power efficiency. In this study, the feasibility of applying a self-biasing circuit through a feedback resistor to a GaN PA MMIC is examined by using the high operation voltage of GaN high-electron mobility transistors. The measured results of the proposed GaN PA are the average output power of 41.1 dBm and the average power added efficiency of 12.2% over the 6-16 GHz band. [ABSTRACT FROM AUTHOR]