An improved technique for the design of an unbalanced analog reflection-type on-chip vector modulator is presented. At microwave frequencies, voltage-controlled high-electron-mobility transistor (HEMT) like pseudomorphic HEMT (pHEMT) is often chosen as the variable termination in vector modulator. However, the parasitic elements of the transistor introduce amplitude and phase errors, which will degrade the overall performance of the vector modulator. Based on the establishment of pHEMT scalable parasitic model and characterization of bond-wire interconnection, we propose a method and a corresponding design procedure that mitigate the parasitic effects of pHEMT and achieve optimum performance of the vector modulator. The influences of Lange coupler characteristic impedance and compensation inductance on the vector modulator are analyzed first. Then, a method to determine the optimal values of characteristic impedance and compensation inductance is given, which relieves parasitic effects and obtains symmetric constellation. In our proposed design, the compensation inductance is realized through bond-wire inductance, eliminating the requirement of the on-chip inductor. To validate the design concept, a vector modulator module, composed of power divider, Lange coupler, and variable termination, is designed with each part fabricated separately using 0.15- $mu ext{m}$ GaAs pHEMT process and assembled on Rogers 5880 substrate with 10-mil-thick printed circuit board. The assembled vector modulator is characterized using an automatic test setup. The measured symmetric constellation is in good agreement with the simulation result, which indicates the effectiveness of the proposed design method and assembly process.
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机译:提出了一种用于设计不平衡模拟反射式片上矢量调制器的改进技术。在微波频率下,通常选择伪晶体HEMT(PHEMT)等电压控制的高电子 - 迁移率晶体管(HEMT)作为载体调节剂中的可变终端。然而,晶体管的寄生元件引入幅度和相位误差,这将降低矢量调制器的整体性能。基于PhEMT可扩展寄生模型的建立和键控互连的表征,提出了一种方法和相应的设计过程,其减轻了PHEMT的寄生效应并实现了矢量调制器的最佳性能。首先分析了Lange耦合器特性阻抗和补偿电感对矢量调制器的影响。然后,给出了一种确定特征阻抗和补偿电感的最佳值的方法,从而减轻了寄生效应并获得对称星座。在我们所提出的设计中,通过键电感来实现补偿电感,从而消除了片上电感的要求。为了验证设计概念,由电源分频器,LANGE耦合器和可变终端组成的矢量调制器模块,每个部件都使用0.15- $ MU TEXT {M} $ GAAS PHEMT流程进行单独制造,并在ROGERS 5880上组装具有10密耳厚的印刷电路板的基板。组装的矢量调制器的特征在于使用自动测试设置。测量的对称星座与模拟结果吻合良好,这表明了所提出的设计方法和装配过程的有效性。
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