用VOLTERRA 级数精确分析 MESFET 功率放大器的副谐波负载牵引特性
ANALYSIS OF THE SUBHARMONIC LOAD PULL CHARACTERISTIC OF THE MESFET POWER AMPLIFIER PRECISELY WITH THE VOLTERRA SERIES METHOD
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摘要: 为了分析CDMA类宽带信号激励下MESFET功放的副谐波负载牵引特性,推导了一组基于MESFET非线性模型的功放电路Volterra转移函数解析式,利用此解析式,建立了三阶交调分量与副谐波负载的解析关系,分析了不同副谐波负载情况下副谐波牵引特性;并推导出了最优副谐波负载的表达式。该文还从两个三阶交调幅度的差异着手,证明了电抗性副谐波负载是造成这一差异的主要因素,上述推导得到的结果与采用ADS软件谐波平衡法仿真得到的结果吻合得很好。Abstract: In order to analyze the subharmonic load pull characteristic of MESFET power amplifier driven by CDMA type wide band signal, a set of Volterra transfer funcion expressions are deducted with the MESFET nonlinear model. With these expressions, the relation between the IM3 (third order intermodulation) and the subharmonic impedance is established, and the characteristic of the subharmonic load pull is analyzed. the expression of the optimal subharmonic load is also given with the analysis. It is proved in the paper that the reactance part of the subharmonic impedance is the main factor that leads to the difference of the two IM3. The result of the analysis agrees well with the simulation result got from ADS with harmonic balance method.
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Xinwei. Wang. et al., A low quiescent current, 40% efficiency three-stage PHEMT power amplifier MMIC for PCS CDMA application, RFIC99, Anaheim, CA, USA, .]une 13 15. 1999. 121-121.[2]J.Staudinger. The importance of sub-harmonic frequency termination in modeling spectral regrowth from CW Am-Am Am-Pm derived nonlinearities, Annual Wireless Communication Conference. Boulder, CA, USA, Aug. 11-13, 1997, 121-125.[3]J. S. Kenney, et al., Power amplifier spectral regrowth for digital cellular and PCS applicatiions.Microwave Journal, 1995, 38(10), 74-92.[4]J.F. Sevic, K. L. Burger, M. B. Steer, A novel envelope-termination load pull method for ACPR optimization of RF/Microwave power amplifiers, 1998 IEEE MTT-S Digest, .June 7-12, 1998.Balimore, BD, USA, 723-726.[5]Wang Xinwei, et al., ACPR, IM3 and their correlation for a PCS CDMA power amplifier, .50th ARFTG Conference Digest, Benson Hotel, Portland, OR, 1997, 91-96.[6]洪兴楠,张向东,用Volterra级数展开表示法分析砷化镓场效应管交调失真,全国微波会议,西安,1985,132-152[7]S.A. Mass. Nonlinear Microwave Circuits, chapter 5, Norword, MA, Artech House 1988. -
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