VARIABLE BANDPASS FILTER AND DUPLEXER USING VARIABLE BANDPASS FILTER

摘要

PROBLEM TO BE SOLVED: To provide a variable bandpass filter having highly selective filter characteristics and high nonleaded Q.;SOLUTION: Resonance circuits comprising parallely connected capacitance circuits, whereof a capacitor Cin and a tunable capacitor Ct with a capacitance component to fluctuate under applied control voltage are connected in series, are connected to strip lines SL1, SL2 with a short circuit end at one end and an open end at the other through a coupling capacitor C2. A control voltage terminal is placed in the connection of the capacitor Cin and the tunable capacitor Ct.;COPYRIGHT: (C)2003,JPO