An energy-efficient and ultra-low-voltage power oscillator in CMOS 65 nm

Abstract

In a direct modulation scheme and particularly in portable and wireless sensor network applications, the oscillator limits the transmitter efficiency therefore, the oscillator efficiency is critical and high-efficiency and high-power oscillators are increasingly required. This paper presents a high-efficiency and ultra-low-voltage power oscillator that operates at 2.4 GHz and is implemented in 65 nm CMOS technology. The power oscillator is a self-oscillating class-E power amplifier (PA) that utilizes a positive feedback system. A class-E PA is selected due to its high efficiency. The power oscillator has an optimized power consumption and output power, where a 2.4 mW power consumption is achieved under a 0.4 V power supply. The proposed oscillator demonstrates a maximum output power of $$-0.45$$ dBm and a peak efficiency of 37.5%. The oscillator is tunable between 1.66 and 2.78 GHz. The oscillator is robust to a $$\pm\,15\%$$ frequency deviation from a 2.44 GHz nominal frequency due to process, voltage, temperature variation.