A PLL circuit compares a PCR with the output frequency of a voltage controlled oscillator (VCO), and returns a voltage value which is the result of the comparison to the VCO, so that a reference clock corresponding to the PCR is outputted from the VCO. A switch supplies a control voltage from the PLL circuit to the VCO when digital broadcasting is viewed, while feeding a fixed voltage from a fixed voltage power supply to the VCO when analog broadcasting is viewed, to stably output a clock having a frequency of 27 MHz irrespective of the change in the PCR.
A display device can simultaneously receive digital display signal and analog display signal and display a television program corresponding to one of the signals on a display panel. The display device includes the following components: a digital tuner, an analog/digital converter, a video decoder, an audio decoder, a de-interlacer, a scaler, a display driver, a display panel, an audio amplifier, and a speaker. The display device allows the user to watch a television program corresponding to the digital display signal or the analog display signal on the display panel and listen to amplified television audio signal from the speaker.
