Design Of 2.2～2.4GHz Doherty Power Amplifier Based On GaAs HBT Process

The new generation of wireless communication technology pursues ultra-high data transmission rate and ultra-wide band,so it has higher demands for the utilization of spectrum resources.This means that the signal modulation mode will be more complex and the signal peak-to-average power ratio will be larger,resulting in the reduced efficiency of the power amplifier.In the 5G era,the large density of base station distribution forced people to focus on energy and cost issues,which promoted the study of high-efficiency power amplifiers.Doherty power amplifier based on GaAs process can achieve high power back-off efficiency,power and linearity,and its structure is simple to realize,so it will be widely used in 5G era.In this paper,a 2.2～2.4GHz Doherty power amplifier based on GaAs HBT process is designed.In order to achieve high gain,the Doherty power amplifier in this paper is designed with four stage power amplifiers,including two driver stages and two Doherty stages.Different from the traditional Doherty power amplifier,the power is divided directly without the use of the power divider,and the large choke inductance and filter capacitors are put outside the chip to reduce the chip area.In this paper,capacitance and inductance networks are used instead of 1/4 wavelength transmission line in traditional structure,thus reducing the chip size.In order to improve the tunability of the chip,the input and output matching networks of the Doherty power amplifier will be realized by the components on the laminate,and the off-chip adjustable positions will be added at the important matching networks.The final measurement results show that the gain of Doherty power amplifier is more than 35.5d B in 2.2～2.4GHz,the input match is less than-14 d B,the output match is less than-7d B,the saturation output power is more than 36.5d Bm,the peak power added efficiency is 40%～45%and the power added efficiency is 37%～40% at 6d B power back off.The ACPR reaches less than-50 d Bc with digital pre-distortion under the LTE 20 MHz signal test condition.The Doherty power amplifier designed in this paper has high efficiency,high power and good linearity,so it can be used in the micro base station of the new generation communication system.