A Linearity-Enhanced mm-Wave GaN MMIC Power Amplifier with Inter-Stage AM/AM Compensation and AM/PM Cancellation

In this paper, a linearity enhanced millimeterwave (mm-wave) Gallium Nitride (GaN) monolithic microwave integrated circuit (MMIC) power amplifier (PA) is presented. The linearity of the proposed amplifier is improved by using the amplitude to amplitude modulation (AM/AM) distortion compensation and the amplitude to phase modulation (AM/PM) distortion cancellation between the driver-stage and the power-stage transistors. For proof of concept, a $26-\mathrm{to}-28-\mathrm{GHz}$ GaN MMIC PA was designed using a $\mathbf{1 2 0 - n m}$ GaN on silicon carbide high electron mobility transistor process. The fabricated amplifier achieves a saturated power of around 30 dBm, with the AM/AM distortion of less than 3-dB and the AM/PM distortion of smaller than 5° from 26 to 28 GHz. The corresponding power-added efficiency (PAE) at saturation is $32.3 \%-35 \%$.