Patent ID: 6891575

Claim:
A digital signal receiving tuner receiving digital signals of a plurality of frequency bands, comprising: an input circuit receiving said signals of a plurality of frequency bands; an input selector circuit receiving the signals from said input circuit to divide the received signals into a plurality of groups according to the frequency bands and selecting and outputting the received signals; a radio-frequency amplification input filter circuit supplied with a band-switching voltage for extracting a received signal of a corresponding frequency band from the received signals supplied from said input selector circuit; a radio-frequency amplifier circuit for amplifying the received signal supplied from said radio-frequency amplification input filter circuit; a radio-frequency amplification output filter circuit supplied with the band-switching voltage for selectively outputting a radio-frequency signal of a predetermined band among radio-frequency signals supplied from said radio-frequency amplifier circuit; an oscillator circuit having a phase-locked loop for supplying said band-switching voltage and outputting a local oscillation signal for each frequency band; and a mixer circuit mixing the radio-frequency signal selected by said radio-frequency amplification output filter circuit and the local oscillation signal from said oscillator circuit to output an intermediate-frequency signal, wherein said oscillator circuit includes a voltage-controlled oscillator provided correspondingly to each frequency band for outputting a corresponding local oscillation signal, and a phase-locked loop circuit constituting the phase-locked loop together with each voltage-controlled oscillator, and wherein said phase-locked loop circuit includes a loop filter formed of a strontium ceramic capacitor.