Lower-frequency feedback dual-band PA with very high efficiency
A novel approach to achieve high-efficiency dual-band power amplifier (PA) is presented. Owing to the contradictions among the control of harmonics, most reported dual-band or multi-band PAs are intentionally avoiding the case when the higher-frequency band overlaps the second harmonics of the lower-frequency band, especially when f higher = 2 f lower . By introducing lower-frequency feedback technique a method is proposed, make a compromise between high-efficiency and power gain fluctuant, high-efficiency dual-band PA at the above condition can be achieved. To verify, a dual-band PA operating at 1.7 and 3.4 GHz is fabricated and measured. The peak output powers of the dual-band are 40.1 and 40.7 dBm with small signal gains 25 and 17 dB, and the drain efficiency at the peak output power reached 80.2 and 78.5%, respectively.