Design of multi-octave power amplifier based on feedback structure of butterworth filter

This paper presents a novel feedback structure for a multi-octave power amplifier (PA). The topological prototype of this structure is the Bartworth low-pass filter (LPF). The passband of the LPF is designed to compensate the PA at the low performance band, enabling the bandwidth (BW) of the PA to be smoothly broadened. To verify the proposed theory, a PA is designed and fabricated using a 10-W GaN HEMT. Measurement results show that the PA operates over a multi-octave band from 0.5-3.0GHz, corresponding to a fractional bandwidth of 142.8%. This PA provides a drain efficiency (DE) of 60.2-80.2% and an output power (Pout) of 39.2-42.1dBm over the operating band.