Highly Efficient Harmonically Tuned Broadband GaN Power Amplifier

The influence of the harmonic impedances on the power amplifier performance is presented across a wide bandwidth. Based on this method, a set of impedances for the first, second and third harmonics across the band was found which do not affect output power (P(out)) and power added efficiency (PAE). At the 3 dB compression point, the measured P(out) is 40 dBm +/- 1.5 dB, and the PAE is between 58.7 %-78.0 % across a bandwidth of 1.5 GHz-2.75 GHz (60 % bandwidth). A linearity measurement was done by sweeping the drain supply voltage, gate bias voltage and injecting a WCDMA drive signal to find the best linearity without affecting the performance. A linearity of -36 dBc at 8.5 dB back-off power from the 3 dB compression point of P(out) was found at 2.15 GHz.