This letter presents a novel reconfigurable, high-efficiency class-F power amplifier (PA) structure, using a commercial GaN-HEMT, that achieves dual-band configuration not only at the fundamental frequency but also at the harmonics. With a proper harmonic tuning structure, the need for an extra filtering section is eliminated, resulting in a high dual-band efficiency with a reduced number of components and size. The reconfigurable structure uses commercial singlepole-double-throw (SPDT) and single-pole-single-throw (SPST) MEMS switches optimally placed on the stubs to select between 900 and 1800 MHz. The reconfigurable PA achieves a measured power-added efficiency (PAE) of 69.5% and a power gain of 13.6 dB while delivering an output power of 39.1 dBm at 900 MHz. At 1800 MHz, the amplifier achieves a PAE of 57.9%, a power gain of 10.5 dB, and an output power of 38.5 dBm.
A novel reconfigurable CMOS class-F power amplifier (PA) at 2.4 GHz is proposed in this paper. It is able to match the output load variations mainly due to the effect of hand and head on a mobile phone. The effect of load variation on PAE, output power and distortion is compensated by reconfiguring the output network using an impedance tuner. The tuner controls the output matching at fundamental frequency without affecting the class-F harmonic tuning up to 3 rd harmonic. To the authors' knowledge, this is the first design of a CMOS class-F PA addressed to compensate the effect of load variation. Measurement results for 50 load impedance show a maximum PAE of 26%, and maximum output power of 19.2 dBm. The measured total harmonic distortion is 4.9%. Measurement results for load values other than 50 show that PAE increases from 6.5% (not-tuned PA) up to 19.9% (tuned PA) with the same output power (19.2 dBm). Tuning also reduces the ACLR by 5 dB and the spectral regrowth of a WiFi signal at the PA output. The size of the fabricated chip is 1.6 mm × 1.6 mm.
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