A novel high frequency, high-efficiency, differential class-E power amplifier in 0.18μm CMOS

This paper presents the design of a high efficiency, low THD, 5.7GHz fully differential power amplifier for wireless communications in a standard 0.18mum CMOS technology. The power amplifier employs a fully differential class-E topology to achieve high power efficiency by exploiting its soft-switching property. In order to achieve high operating frequency, an injection-locked oscillator is utilized, which makes the output voltage of the power amplifier tuned at the input signal frequency. A complementary CMOS cross-coupled pair topology is employed to realize the LC-tank oscillator because it has lower phase-noise, thereby giving lower THD than the single NMOS cross-coupled pair topology. The proposed power amplifier can deliver 25dBm output power to a 500 load at 5.7GHz with 42.6% power-added efficiency (PAE) from 1.8V supply voltage.