LDMOS线性微波功率放大器设计

LDMOS以其大功率、高线性度和高效率等优点得到广泛的应用.采用2-tone负载牵引法得到了LDMOS晶体管MRF18030的输入和输出阻抗.在对晶体管绝对稳定性分析的基础上,运用共轭匹配法设计出匹配网络,并将匹配网络转化为MOMENTUM元件运用在电路设计中,大大提高了设计的准确性.采用载波复幂级数法对PA的AM-AM和AM-PM非线性特性进行了准确计算,弥补了传统泰勒级数只能分析AM-AM的不足.得到了用来消除PA非线性的反载波复幂级数.根据所得反载波复幂级数,利用二极管非线性特性设计出一种新的结构简单、易于实现的预失真器,给出其准确的电路模型表达式,得到了幅值、角度等参数的精确值.ADS仿真结果表明,IMD3改善了27dB.最终,成功设计出大功率、高效率、高线性的LDMOS微波功率放大器.

LDMOS Linear Microwave Power Amplifier Design

LDMOS is widely applied for its high linearity gain and efficiency.The input and output impedance of MRF18030 transistor are obtained by 2-tone load-pull method.Matching networks,which are changed into corresponding MOMENTUM components and used in schematic designing with well improvement design accuracy,are designed by the conjugate match method basing on the analysis of unconditional stability.A new method of carrier complex power series(CCPS),which accurately calculate the nonlinearity AM-AM and AM-PM synchronously,has advantage over classical Taylor series in which only the AM-AM can be analyzed.In order to eliminate the nonlinearity of PA,according to the expression of inverse CCPS(ICCPS),a linearizer predistorter,simple in configuration and easy to implement,is designed and simulated by using the nonlinearity of diode.The accurate expression of circuit model is deduced and precise value of amplitude and angle are obtained.ADS simulation results show that IMD3 is improved by 27 dB.Finally,LDMOS microwave power amplifier of high power high efficiency and well linearity is successfully designed.