Design of Adaptive Highly Efficient GaN Power Amplifier for Octave-Bandwidth Application and Dynamic Load Modulation

This paper presents a novel adaptive power amplifier (PA) architecture for performing dynamic-load-modulation. For the first time, a dynamically-load-modulated PA design that achieves octave bandwidth, high power and high efficiency simultaneously is experimentally demonstrated. This PA design is based on a commercial GaN HEMT. The output matching scheme incorporates a broadband static matching for high-efficiency at the maximum power level and a wideband dynamic matching for efficiency enhancement at power back-offs. The impedance and frequency tunability is realized using silicon diode varactors with a very high breakdown voltage of 90 V. Experimental results show that a dynamic-load-modulation from maximum power to 10-dB back-off is achieved from 1 to 1.9 GHz, with a measured performance of ≈10-W peak power, ≈10-dB gain, 64%-79% peak-power efficiency, and 30%-45% efficiency at 10-dB power back-off throughout this band.