| 摘要 |
PROBLEM TO BE SOLVED: To provide a frequency variable impedance matching circuit which is capable of easily obtaining a value expected to be possessed by a variable capacitor even if circuits are increased in the number of stages and keeping an impedance transformation ratio constant even if an operating frequency is varied in a wide range of frequency band. SOLUTION: A circuit formed of a transmission line of fixed length and a pair of variable capacitors connected to the ends of the transmission line, respectively, or a circuit formed of a transmission line of fixed length and a variable capacitor connected to the middle point of the transmission line is made to serve as a unit circuit, and an even number of the unit circuits whose transmission lines are of the same fixed length are cascade-connected together. By the arrangement, even if the unit circuits which are cascade-connected are increased in the number of stages so as to obtain a large impedance transformation ratio, a value expected to be possessed by a variable capacitor can be easily obtained, and an impedance transformation ratio can be always kept constant even if an operating frequency is varied in a wide rage of frequency band. COPYRIGHT: (C)2006,JPO&NCIPI
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