INTERMEDIATE FREQUENCY CIRCUIT FOR TV RECEIVER

摘要

PROBLEM TO BE SOLVED: To cancel voltage controlled oscillator(VCO) distortion without using an inverted amplifier. SOLUTION: An input signal from a +45 deg. phase shifter 6 to a phase comparator 3 is made into phase difference at 90 deg. to an intermediate frequency(IF) signal and the IF signal and the video signal of an opposite phase is provided from an IF detector 8 but by differentially inputting it to a video signal amplifier 9, the video signal of a common mode with the IF signal is provided from the video signal amplifier 9 and by superimposing this signal through an SIF trap filter 10, an equalizer amplifier 12 and a filter 14 for video signal extraction to the output signal of a PLL filter 4, the VCO distortion residual in the output signal of the PLL filter 4 is canceled by the opposite phase component from the filter 14 for video signal extraction.