Design and application of automatic impedance matching circuit

• Main Authors: CHIN-CHENG WANG, 王金城
• Other Authors: Rong-Chan Hsieh
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/94800665029695541599

碩士 === 華梵大學 === 電子工程學系碩士班 === 93 === This thesis is devoted to the “design and application of automatic impedance matching (AIM) circuit”. This AIM circuit is mainly composed by three blocks, (1) tunable impedance matching (TIM) circuit, (2) six-port reflectometer, (3)integrate and control software. In this thesis, the design method of TIM is modified for better performance. The RF parasitic effect of switching diode in the TIM is studied and compensated by simple method. Experimental result shows that the modified TIM circuit has predicted performance. This TIM circuit can be controlled by 9 dc signal lines to obtain 512 tunable impedance matching points. Experimental result shows that these matching points are closed to the simulation results. More important, these points are distributed uniformly over the smith chart. This means the TIM circuit has a wide matching area over the smith chart. In the configuration of this thesis, the six-port reflectometer, which is designed by another colleague in the same Lab, is used to accurately measure the reflection coefficient of the device under matching (DUM). By using these vector measuring data, the AIM system can automatically and efficiently do the optimal impedance matching work. In order to achieve the designed purpose of AIM, a Labview program is written on a personal computer (PC) to control and integrate the function of TIM and six-port reflectometer respectively via the GPIB and print port interfaces. Experimental result shows that this AIM system can automatically and efficiently match the DUM over broad impedance range. This AIM system can further be developed to be a dynamic matching system. This may meet the further requirement of modern mobile communication system.