| 摘要 |
A combined analog and digital tuner is provided to simplify a circuit and reduce size of the combined analog and digital tuner by demodulating an analog video signal without a video surface elastic wave filter by demodulating the analog video signal of an intermediate frequency signal outputted through an MOPLL integrated circuit through a selecting switch part and an orthogonal frequency division multiplexing surface elastic wave filter. An MOPLL(Mixer Oscillator Phase Locked Loop) integrated circuit(20) mixes an inputted high frequency signal with local oscillating frequency according to a frequency band for outputting an intermediate frequency signal. An audio surface elastic wave filter(21) is connected with an output end of the MOPLL integrated circuit and filters only an audio signal from the intermediate frequency signal outputted from the MOPLL integrated circuit. A selecting switch part(22) is connected with the MOPLL integrated circuit, and has a trap circuit(221) preventing interference of adjacent frequencies. An orthogonal frequency division multiplexing surface elastic wave filter(23) is connected with the selecting switch part and filters the intermediate frequency signal inputted through the selecting switch part with a digital signal passing band, which is able to filter both a video signal and a digital signal.
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