A High Power High Efficient 5.8 GHz CMOS Class-A Power Amplifier for a WPT Application

This paper presents a high power and highly efficient 5.8 GHz differential two-stage cascode Class-A Power Amplifier (PA) for a Wireless Power Transfer (WPT) system. The PA is designed in a standard General Purpose (GP) 180 nm CMOS technology. The process does not apply any Radio Frequency (RF) devices such as inductor nor transformer which are essential for an RF design. A full custom-made transformer is proposed and optimized at 5.8 GHz which is modeled using EMX analysis. The proposed transformer shows 1.5 nH and 1.28 nH inductance at the primary and secondary sides of the transformer while their quality factor reaches up to 11.4 and 11 at 5.8 GHz, respectively. Even though reaching higher efficiencies in CMOS processes is more challenging than the GaN processes, the proposed PA has a relatively high Power Added Efficiency (PAE) of 33%. The power gain of the PA is 19.47 dB at 5.8 GHz. The average current consumption of the PA is 144 mA while the power supply is 1.8V.