This paper studies the influence of the gate voltage of the power amplifier (PA) on the drain current and efficiency. This study proposes a theory of controlling input non-linearity to improve the efficiency of PAs. The theoretical efficiency of the inverse Class F PA which controlling input non-linearity is from 77 to 97%. A new design method for the inverse Class F PA that reconstructs the design of the load admittance space into a region instead of a point. To verify the validity of the proposed theory, a inverse Class F PA is designed and fabricated using a commercial 10W GaN high electron mobility transistor (HEMT). Results of the measurement show a high drain efficiency (DE) of 78.5%, a output power of 41.6 dBm and a large signal gain of 12.1 dB at 1.5 GHz. The overall PA’s size is controlled at 80*50 m m 2 .

This letter presents a broadband high-efficiency power amplifier (PA) based on a series of continuous modes (SCMs). A novel filtering matching network is proposed for realizing the output matching network (OMN) of the PA. The network consists of a branch-loaded cascade-coupled microstrip line structure (BLCCMLS) and a harmonic control network (HCN). The cascaded coupled microstrip line extends the bandwidth of the filter, and this filtering OMN has high bandpass selectivity and high out-of-band rejection, which improves the efficiency of the PA. For demonstration, a 10W GaN HEMT device is used to design and implement a PA. The measurement results indicate that the designed PA achieved an output power (Pout) of 38.7-42 dBm, a drain efficiency (DE) of 60.5%-74.1%, and a gain of 8.7-12 dB at 2.05-2.7 GHz.

This letter proposes a novel design method for resistive-resistive series of continuous modes (Res-Res SCMs) power amplifier (PA), which can extend the bandwidth of the SCMs PAs. Using a waveform engineering method, by introducing resistive part to the purely reactive second harmonic load of the series of continuous modes, overcoming the bandwidth limitation of traditional continuous PAs within one octave due to the inability to overlap between low band and high-order harmonics and high band fundamental waves. An ultra-wideband PA working across 0.4–3.1 GHz (154.3% bandwidth) is simulated and fabricated using a 10 W GaN HEMT device, the experimental results show that a drain efficiency of 63%−81.7% can be achieved with a saturated output power of 38.6−42.3 dBm in the desired design band.