An X-Band Low-Voltage Gan Hemt Stacked Power Amplifier Operating in Class-J with Active Second Harmonic Injection

This paper describes a stacked power amplifier (PA) operating in Class-J mode over <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$9.0-10.0 \text{GHz}$</tex> in which the efficiency of the PA is enhanced by active second harmonic (2f) injection. Sony's GaN HEMT technology is employed to obtain high power at low supply voltage. A small-signal gain of 24.0 dB with continuous-wave saturation output power of 34.2 dBm and power-added efficiency of 56.2 % together with a final stage drain efficiency of higher than 70 % are achieved at 9.5 GHz at a supply voltage of 5 V. The chip size is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1.2 \text{mm}^{2}$</tex>.