High linearity U-band power amplifier design: a novel intermodulation point analysis method

A power amplifier's linearity determines the emission signal's quality and the efficiency of the system. Nonlinear distortion can result in system bit error, out-of-band radiation, and interference with other channels, which severely influence communication system's quality and reliability. Starting from the third-order intermodulation point of the milimeter wave (mm-Wave) power amplifiers, the circuit's nonlinearity is compensated for. The analysis, design, and implementation of linear class AB mm-Wave power amplifiers based on GlobalFoundries 45 nm CMOS silicon-on-insulator (SOI) technology are presented. Three single-ended and differential stacked power amplifiers have been implemented based on cascode cells and triple cascode cells operating in U-band frequencies. According to nonlinear analysis and on-wafer measurements, designs based on triple cascode cells outperform those based on cascode cells. Using single-ended measurements, the differential power amplifier achieves a measured peak power-added efficiency (PAE) of 47.2% and a saturated output power (P-sat) of 25.2 dBm at 44 GHz. The amplifier achieves a P-sat higher than 23 dBm and a maximum PAE higher than 25% in the measured bandwidth from 44 GHz to 50 GHz.