| 摘要 |
The broadband receiving circuit for a television or a video tape recorder converts the received HF signal into the IF signal by up- conversion and demodulates the IF signal by the direct synchronous detection. The circuit comprises an automatic gain control section (100), a control section (200) for producing the selection control signal, first and second band selection section (300,400) for extracting VHF and UHF signals from the output of the automatic gain control section, a local oscillation section (500), an IF conversion section (600) for up-converting by mixing the local oscillation frequency with one from the outputs of two band selection sections, and a sync. detection section (700) for demodulating the video and audio baseband signals. |
