Patent ID: 6678011
Filing Date: 2004-01-13
Classification: H04N

Abstract:
A frontend circuit comprising:a first bandpass filter for separating and taking out an audio intermediate frequency signal from an input composite intermediate frequency signal; a first A/D converter circuit for A/D converting the audio intermediate frequency signal taken out by the first bandpass filter into a digital audio intermediate frequency signal; a first DSP for performing audio detection on the digital audio intermediate frequency signal that is output from the first A/D converter circuit and for forming a first AGC signal based on the digital audio intermediate frequency signal; a variable gain amplifier provided on a signal line between the first bandpass filter and the first A/D converter circuit for performing AGC on the audio intermediate frequency signal using the first AGC signal; a second bandpass filter for separating and taking out a video intermediate frequency signal from the input composite intermediate frequency signal; a second A/D converter circuit for A/D converting the video intermediate frequency signal taken out by the second bandpass filter into a digital video intermediate frequency signal; and a second DSP for performing video detection on the digital video intermediate frequency signal that is output from the second A/D converter circuit and for forming a second AGC signal based on the digital video intermediate frequency signal, wherein AGC is performed on the input composite intermediate frequency signal using the second AGC signal.