Design of a Millimeter-Wave Power Amplifier Based on Input Nonlinearity and Continuous Waveforms

This letter presents a design of gallium nitride (GaN) millimeter-wave power amplifier (PA) that exploits the input nonlinear characteristics and continuous waveforms to improve efficiency and extend design space. Unlike the conventional Class-F<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> that excludes the second-harmonic current component, the proposed design considers the role of second-harmonic component generated by input nonlinearity to manipulate current waveforms. Based on the modified Class-F<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup>J with continuous voltage waveforms, a closed-form solution is derived to simultaneously achieve second-harmonic suppression and expansion of design space. For verification, a 23–30-GHz single-stage PA with third-order low-pass filter matching networks is implemented in a 0.15-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula>m GaN process. It achieves 24%–35% power-added efficiency (PAE) with more than 26-dBm saturated output power. When excited by a 400-MHz 5G new radio (NR) signal with digital predistortion (DPD), it shows better than −40 dBc adjacent channel leakage ratio (ACLR) and less than 3% error vector magnitude (EVM) over the frequency band.