Design of a class EF2 power oscillator for RF communication application

A power oscillator based on a class EF2 power amplifier is presented. The class EF2 power amplifier uses a short circuit to the second harmonic across the switch to lower it's voltage stress and delivers a more sinusoidal power waveform than the class E counterpart. The presented circuit was designed in standard ST Microelectronics CMOS 130nm and is able to deliver 20.6dBm RF power from a 2V supply voltage with a 42% DC-RF efficiency at 2.5GHz and present 12.5% tuning range. The drain efficiency of the class EF2 core is 49.4%. The phase noise is as low as -118.8dBc/Hz @ 1MHz. The output power spectrum presents 30.7dB power difference between the fundamental frequency and the strongest upper harmonic. The total used area is 1550um × 1280um.