High Efficiency and High Linearity 70 nm GaN Technology for Future SatCom Applications

In this work, we report on the development of a high efficiency and high linearity 70 nm GaN power amplifier technology. DC-characteristics reveal a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{g}_{\mathrm{m}, \max } \approx 500 \text{mS} / \text{mm}$</tex> and low DC to pulsed-IV current collapse (< 15%). Small signal characteristics exhibit a cutoff frequency of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{f}_{T}=122 / 95 \text{GHz}$</tex> at V <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$_{\text{DS }}=7 / 15 \mathrm{V}$</tex> as well as an <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathrm{f}_{\text{MAX }}&gt;350 \text{GHz}$</tex>. Large-signal characteristics give a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{PAE} (\text{MAX}) =58.6 \%$</tex> and maximum output power <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\text{Pout} (\text{MAX})=2.46 \mathrm{W} / \text{mm}$</tex> at 38 GHz. Signal linearity was assessed by two-tone load-pull measurements which gave an PAE <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$=54.4 \%$</tex> and Pout <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$=1.01 \mathrm{W} / \text{mm}$</tex> under back-off conditions (IMD3<30 dBc) in line with SatCom requirements. Efficiency under back-off conditions is among the highest reported values in any GaN-technology on a transistor level so far, which demonstrates the potential use in future applications.