线性Doherty功放的优化设计  

Optimized Design of Linear Doherty Power Amplifier

作　　者：向永波[1] 王光明[1] 

机构地区：[1]空军工程大学,三原713800

出　　处：《微波学报》2010年第1期72-75,共4页Journal of Microwaves

摘　　要：设计了一个高效率、高线性度的射频Doherty GSM基站功放。利用Doherty功放的载波放大器与峰值放大器之间的互调对消技术使Doherty功放的三阶互调干扰(IMD3)改善了11dBc;并通过相位补偿延迟线的前置处理进一步提高了功放的效率,使其效率比常用的平衡补偿线方案提高了4%左右。文中利用两个MRF9060功放管制作了一个GSM频段Doherty功放,其实测1dB压缩点功率(P1dB)达到了130W;双音测试表明:经过4.5dB的回退后三阶互调失真(IMD3)优于-35dBc,此时功率附加效率(PAE)高达47.3%;WCDMA 3GPP的测试结果表明:经过6dB回退后,其5MHz偏移量的邻道功率比(ACPR)优于-40.5dBc,PAE为43.5%,比AB类平衡功放的效率提高了17.8%。结果表明:该设计方案较好地解决了射频功放功率与效率之间的矛盾,适用于射频功放的设计。A Doherty power amplifier （DPA） with both high efficiency and good linearity for GSM base-station was presented in this paper. The Third-order intermodulation distortion （IMD3） of the DPA has improved about 1 ldBc using intermodulation cancellation technique between the peaking amplifier and the carrier amplifier; and the high efficiency was enhanced by the disposal of a prepositive phase offset delay line, and a 4% efficiency enhancement was reached. The DPA was realized using two MRF9060 power transistors in GSM band, the tested P1 dB was 130W; two tone test showed the third-order intermodulation distortion （ IMD3 ） was better than - 33dBc at 4.5dB back-off power point （ BOP）, while the relevant power added efficiency （PAE） was about 47.3% ; and the adjacent channel power ratio （ACPR） was better than -40.5dBe at 5MHz offset after 6dB BOP under W-CDMA 3GPP test signal, while the relevant PAE was 43.5%, which was about 17.8% improvement than a balanced class AB power amplifier. The results showed the method had solved the conflict between the efficiency and the linearity problem very well to a RF power amplifier, and suitable for the design of the RF power amplifier.

关 键 词：DOHERTY功放 三阶互调失真 邻道功率比 效率 

分 类 号：TN722.75[电子电信—电路与系统] TP213[自动化与计算机技术—检测技术与自动化装置]