南京大学学报：自然科学版2012，Vol.48Issue(5)：671-676,6.
补偿网络对Cascode结构放大器线性度的改善
Improvement of linearity in Cascode broadband amplifier by resistance-inductance-capacitance compensation network
摘要
Abstract
With the development of wireless communication,the system needs to cover multiple frequency bands for different standard;therefore broadband power amplifiers will play a more and more important role in multi-band power amplifier modules(PAMs).The cascode structure,composed of a common-emitter(CE) and a common-base(CB) transistor,is widely used in the broadband power amplifier design because of its miller effect capacitance suppression and high output impedance.RLC peaking technology is a well-known approach to broaden the bandwidth of cascode power amplifiers.In this approach,a RLC peaking network,also called resistance-inductance-capacitance(RLC) loss compensation network,is placed at the base of a common-base transistor,instead of a DC blocking capacitor in the conventional cascode structure.According to previous research,different working conditions of the transistors in the cascode structure will lead to a noticeable influence on the linearity of the whole power amplifier.However,in addition to broad bandwidth,the linearity is another key figure-of-merit for a high quality system.The paper presents a method to improve both bandwidth and linearity of a cascode broadband power amplifier.The optimization can be accomplished by adjusting the values of the components of the RLC peaking compensation network to make the active devices work in the maximum linear dynamic range.As a result,both of an improvement in the linearity and high power added efficiency can be achieved.This paper presents the optimization principles of the components' values of the RLC peaking compensation network,and explains the reason why a higher linearity is achieved without degradation of power added efficiency.Moreover,a numerical analysis of the 3rd order intercept point(IP3) based on Volterra Series method demonstrates that the IP3 could be improved by about 3 dB using this optimized components' values of RLC peaking compensation network.Finally two cascode power amplifiers,which are with the RLC peaking compensation network after optimization and without the RLC peaking compensation network respectively,are designed,and fabricated in 2 μm InGaP/GaAs hetero-junction bipolar transistor(HBT) technology from Advanced Wireless Semiconductor Corporation.The measurement results show that the IP3 of the power amplifier with RLC compensation network can be improved by 3 dB in the operation band and the 3dB bandwidth is broadened to 1 GHz(from 1.5 GHz to 2.5 GHz).That is in agreement with the theoretical analysis.关键词
补偿网络/Cascode放大器/线性度/Volterra/SeriesKey words
resistance-inductance-capacitance peaking compensation network/cascode amplifier/linearity/volterra series分类
信息技术与安全科学引用本文复制引用
张晓东,王钟,高怀,程建春,吴浩东..补偿网络对Cascode结构放大器线性度的改善[J].南京大学学报：自然科学版,2012,48(5):671-676,6.基金项目
国家自然科学基金 （）
江苏省科技支撑计划——工业部分 （）
