Small integrated second frequency converter

In recent years, with the development of microwave and ultra-high frequency integrated circuit technology, ultra-high frequency circuits composed of discrete components in satellite receivers are
gradually being replaced by integrated small circuits. Shown in the figure is a small integrated third frequency converter with high integration, small size and good reliability
. The first intermediate frequency signal
(950-1750 MHz)     from the tuner (BS frequency converter) first undergoes low-noise amplification through a two-stage RF amplifier , and then passes through an image suppression filter to eliminate the interference of the image frequency. The first intermediate frequency signal of the satellite program is frequency differenced with the second local oscillator signal sent from the local oscillator circuit (vco) in the frequency converter , and forms a second intermediate frequency signal. The second intermediate frequency signal is amplified by a multi-stage intermediate frequency amplifier. An intermediate frequency band-pass filter (BPF) is provided in the multi-stage intermediate frequency amplifier circuit to improve the anti-interference ability. Finally, the second intermediate frequency signal is processed by a phase-locked loop demodulator. The signal is demodulated and a baseband signal is output.