应用于LTE基站的L波段Doherty放大器

射频功率放大器是现代无线通信系统中的重要组成部件之一,传统的功率放大器设计非常依赖射频工程师的工程经验,一般通过实物电路的反复调试达到设计指标.采用Doherty技术设计并实现了一种应用于长期演进(long term evolution,LTE)移动通信技术基站的L波段高效率功率放大器.设计中采用了安捷伦公司的先进设计系统软件,选取恩智浦公司型号为AFT20P140-4WN的横向扩散金属氧化物半导体(laterally diffused metal oxide semiconductor,LDMOS)功放晶体管,该晶体管工作频段为1 880 MHz~2 025 MHz.通过电路仿真与实物调试相结合的方式完成了整个设计.测试结果表明,所设计Doherty功率放大器的最大输出功率为45.3 dBm,最高效率为37%,在4.2 dB功率回退的情况下,效率仍保持在30%左右.与传统的功率放大器设计相比,此设计方式缩短了设计周期,提高了设计成功率并降低了设计成本.

L-band Doherty amplifier for LTE base station

The radio frequency power amplifier is one of key components in modern wireless communication system. The traditional design method depends on the experiences of the engineers. The indexes can be reached by debugging the circuit repeatedly. In this paper, an L band high efficiency power amplifier with Doherty technology for long term evolution (LTE) base station is proposed. During the design, the advanced design system (ADS) of Agilent company is applied, and the lateral diffused metal oxide semiconductor (LDMOS) transistor AFT20P140-4WN of NXP company is adopted. The operating frequency is between 1 880 MHz and 2 025 MHz. The design is accomplished by combing the simulation and circuit debugging. According to the measurement results, the biggest output power of the Doherty power amplifier is about 45.3 dBm, the largest efficiency is approximately 37%. Especially, the efficiency is still around 30% when the power back off is about 4.2 dB. Compared with the traditional method, this design method can shorten the design cycle, improve the design success rate and reduce design costs.