| With the rapid development of modern communication technology,low-frequency spectrum resources are increasingly scarce.The millimeter wave frequency band is rich in available spectrum,which can support higher-speed data transmission and meet the requirements of fifth-generation(5G)communications.Due to the continuous improvement of CMOS manufacturing process,and the advantages of easy integration and low cost,it is widely used in millimeter wave circuits.The transmitter is one of the main modules used to transmit signals in the communication system.The power amplifier is applied to magnify the radio frequency signal to the desired output power so that the signal can reach the receiver.It can be seen that the use of CMOS technology to design a high-performance power amplifier to meet the changing needs of communication systems has profound research significance.This article uses 65 nm CMOS process to design two power amplifiers for 5G frequency band.The main contents are as follows:1.Investigated the technical types of power amplifiers.The important indicators of power amplifiers are introduced,and the operating principles of different power amplifiers are analyzed to determine the forms of power amplifiers.2.Explain the design methods of power amplifiers,analyze the models of active transistors and passive devices in CMOS technology,and explain the impact and challenges of transistor performance parameters on circuit design.The influence of transistor size on circuit performance parameters is analyzed through simulation,which provides a reference for the selection of transistor size.The design principles and methods of conjugate matching and load line matching theory are deeply analyzed,and the matching network is introduced.3.Based on the 65 nm CMOS process,two power amplifiers adapted to the millimeter wave 5G frequency band are designed.The first is a single-ended structure,the driver stage is a cascode structure,and the output stage is a common source structure.Self-biasing technology is applied in the cascode structure to improve the voltage endurance of the transistor.The matching network is used to reduce the loss caused by signal reflection.Under 1.2 V supply voltage,the gain of the circuit is 21 dB,the saturated output power is 14.7 dBm,and the efficiency is 18%.To further improve the output power,the second circuit adopts a two-stage differential common source structure to achieve.The cross-coupling capacitors mitigates the parasitic effects of the circuit,and enhance the gain,stability and efficiency performance of the circuit.Under 1.2 V supply voltage and 28 GHz operating frequency,the saturation output power of 17 dBm and efficiency of 21% are realized,and the gain can reach 18 dB. |
