VOLTAGE CONTROLLED HIGH FREQUENCY BAND-PASS FILTER

PURPOSE:To attain the miniaturization and low cost of the high frequency BPF of portable radio equipment for 800MHz band. CONSTITUTION:BPFs 3, 6 with band width narrower than a working band comprises dielectric resonators 11, 12 by capacitance coupling, and voltage variable capacitance elements 14, 16 are connected to the dielectric resonators 11, 12 in parallel. The correspondence relation of a DC voltage value supplied to the voltage variable capacitance elements 14, 16 and the center frequencies of the BPFs 3, 6 is found by experiment in advance, and an analog-converted DC voltage is supplied to the voltage variable capacitance elements 14, 16 by outputting data in accordance with channel in use from a CPU 9 which controls a tuned channel, and the center frequencies of the BPFs 3, 6 are shifted to a tuned channel frequency.