The Second Source Harmonic Optimization in Continuous Class-GF Power Amplifiers

In this letter, the second source harmonic in continuous-mode class GF (CCGF) is optimized to flatten the power amplifier's (PA) frequency response over a wideband. A new design space is explored by considering the effects of controlling the input nonlinearity of the gate-source capacitance ( C_{\mathrm {gs}} ) on the drain current waveforms under continuous-mode drain voltage waveforms. A wideband CCGF PA is designed and fabricated using a commercial 10-W gallium nitride (GaN) device and low-temperature co-fired ceramic (LTCC) technology. Results of the measurement show a flat frequency response from 3.3 to 4.3 GHz with variations less than ±0.4 dB for 40 dBm output power, and 17 dB large signal gain at 3-dB compression point. A drain efficiency of 66 ± 2% is achieved over the entire bandwidth.