Stereo-phonic frequency modulation receiver and method for separating dual sound channels

A stereo-phonic frequency modulation receiver, comprising:

• a frequency modulation demodulation circuit, receiving a reception signal, and generating a demodulated signal according to the reception signal;
• a frequency-division demultiplexer, generating a sum signal, a difference signal and a pilot amplitude signal according to the demodulated signal, wherein the sum signal is associated with a sum of a left sound channel and a right sound channel, and the difference signal is associated with a difference between the left sound channel and the right sound channel;
• a dual sound channel separation circuit, generating a left-channel output signal and a right-channel output signal according to the sum signal and a weakened difference signal;
• and
• a weakening circuit, coupled between the frequency-division demultiplexer and the dual sound channel separation circuit, weakening the difference signal according to the pilot amplitude signal or a signal-to-noise ratio (SNR) to generate the weakened difference signal,
• wherein the frequency-division demultiplexer comprises:
• a first low-pass filter (LPF), receiving the demodulated signal and generating the sum signal;
• a frequency multiplier, generating a frequency multiplied signal according to an oscillation signal;
• a band-pass filter (BPF), receiving the demodulated signal and generating a band-pass filtered result;
• a mixer, generating a mixed result according to the frequency multiplied signal and the band-pass filtered result;
• a second LPF, receiving the mixed result and generating the difference signal;
• and
• an amplitude circuit, generating the pilot amplitude signal according to the pilot signal.