| 摘要 |
A radio frequency filter comprising several resonator circuits, such as duplex filter, is provided with a given passband. Signal frequencies generating spurious response, mirror frequencies, etc. can be effectively attenuated so that the filter comprises one more resonator circuit connected as a bandstop circuit. That comprises a transmission line resonator (Res), a series connection of an inductive element (MLIN2) and a capacitance diode (D), one end of the series connection being coupled to a coupling point in the transmission line resonator, dividing it into two parts (TLIN1, TLIN2), and the other end being coupled to the output connector (1) of the radio frequency filter. In addition, means are provided for carrying the direct voltage (V+) to the cathode of the capacitance diode, whereby the series resonance frequency changes according to the control voltage. <IMAGE> |
