电缆分布电容引起的宽带放大电路自激振荡探讨  

Discussion on Self-Excited Oscillation of Broadband Amplifier Caused by SMA Long Cable Distributed Capacitance

作　　者：黄明 丁照雨 李争平 徐德仁 HUANG Ming;DING Zhangyu;LI Zhengping;XU Deren(North China University of Technology,Beijing 100144,China)

机构地区：[1]北方工业大学电子信息工程学院,北京100144

出　　处：《电子器件》2018年第2期395-399,共5页Chinese Journal of Electron Devices

摘　　要：针对宽带放大电路中SMA长缆易导致自激振荡的现象,研究了其分布电容对运算放大器性能的影响,并提出在运放的输出端和负载电容之间串入一50Ω电阻的解决方法。采用TI的OPA691芯片设计完整放大电路,运用Tina仿真分析容性负载驱动电路的频率响应,仿真显示,当加入容性负载后,再加入50Ω电阻可使-180°相位时的幅度特性为-12.26 d B,远小于0 d B。经过电路实测,自激振荡消失,验证了该解决方案的合理性。Aiming at the phenomenon that the SMA cable in the broadband amplifier circuit is easy to cause self-oscillation,the influence of the distributed capacitance on the performance of the operational amplifier is studied,and a solution to the 50Ωresistor between the output terminal and the load capacitance is proposed.Amplification circuit’s design uses TI’s OPA691 chip,according to the Tina simulation analysis for frequency response of the capacitive load drive circuit,it shows that when the capacitive load is added,the 50Ωresistor can make-180°phase amplitude to-12.26 dB,much smaller than 0 dB.In the circuit measurement self-oscillation disappeared,the rationality of the solution has been verified.

关 键 词：运算放大电路 容性负载 自激振荡 频率响应 负反馈 

分 类 号：TN721.1[电子电信—电路与系统]