SIGNAL PROCESSING CIRCUIT AND TELEVISION SIGNAL RECEIVER

摘要

PURPOSE: To provide a television signal processing circuit suitable for making it into an IC by attaining an AM detector for which a phase shifter for mutually phase shifting video intermediate frequency(VIF) input or the like is eliminated. CONSTITUTION: Video intermediate frequency(VIF) signals are respectively supplied to a frequency discriminator 42a and the AM detector 41c and the discrimination output of the frequency discriminator 42a is supplied through a low-pass filter 42b to a voltage controlled oscillator 42c. The first oscillation output of the voltage controlled oscillator 42c is supplied to the frequency discriminator 42a and a PLL block 42 is turned to a lock state. In the meantime, second oscillation output phase shifted for 90 degrees to the first oscillation output is supplied from the voltage controlled oscillator 42c to the AM detector 41c and the AM detector 41c synchronously detects the video intermediate frequency signals and demodulates the video signal output of a base band. The output of the low-pass filter 42b is generated as AFT output by a reference circuit 42d.