Switched capacitor bandpass filter for detecting pilot signal

摘要

An apparatus for detecting a pilot signal. A phase detector detects a phase difference between a filtered amplitude-modulated pilot signal and a frequency divided signal, and a low pass filter low-pass-filters the phase difference. A voltage-controlled oscillator outputs a clock signal having a frequency determined by an output signal of the low-pass filter and outputs the clock signal having the frequency determined by an oscillation control signal. A (1/N) frequency divider divides the switching signal and outputs the (1/N) divided signal as a frequency divided signal, and an envelope detector detects an envelope of the filtered amplitude-modulated pilot signal and outputs the detected envelope as the pilot signal. The frequency of the pilot signal has information used to discriminate a broadcasting state. Therefore, the manufacturing cost and the number of pins in an integrated circuit can both be reduced.