| 摘要 |
PURPOSE:To prevent the spurious deterioration of wide band reception by controlling voltage variable capacity elements which are added to BPFs of the high frequency part of a radio receiver by the phase comparator output of a PLL, and varying the center frequency of the BPF. CONSTITUTION:In the radio receiver which has a local oscillator PLL synthesizer, an error signal is branched from the phase comparator 8 of the PLL; one is inputted to an LPF9 and the other is inputted to a control voltage generator 12. Voltage variable capacity elements 13, 14, and 15 are added to the BPFs 1, 2, and 3 of the high frequency part to allow variation in center frequency with a voltage, and the elements 13-15 are driven by the output of the generator 12. The error voltage of a comparator 8 varies in output DC voltage with the frequency, so the center frequencies of the BPFs 1-3 are varied with a local oscillation frequency. Thus, a wide band receiver is realized without deterioration of the spurious sensitivity, etc. |
