A 28-GHz Current-Mode Inverse-Outphasing Power Amplifier in 65-nm CMOS

In this paper, a 28-GHz high efficiency outphasing power amplifier (PA) with Chireix compensation in 65-nm Silicon-On-Insulator (SOI) CMOS technology is proposed. To improve the power-back-off (PBO) efficiency, the PA uses a current-mode inverse outphasing architecture, which supports compatibility with current-mode PAs, highly efficient active load modulation. Meanwhile, the neutralization capacitor and source degeneration inductor technology is employed to tradeoff linearity and high efficiency requirements. At 28GHz with a supply voltage of 2.5/1.2V, the complete outphasing PA achieves a simulated saturated output power of 23.8dBm with 45.1% power-added efficiency (PAE) and 6dB back-off PAE of 25.2%, 1-dB compression output power of 21.8dBm, and gain of 16.6dB. The simulation results also show that the PA is unconditionally stable in the whole working frequency band. The power amplifier has a layout size of 1.02 mm(2) and a core area of 0.46 mm(2).