DOUBLE PLL OF DOUBLE CONVERSION TYPE TUNER

摘要

PURPOSE: A double PLL(Phase Locked Loop) of a double conversion type tuner is provided to improve the efficiency of operation by using a simple structure of a temporal memory device. CONSTITUTION: An I/R reference divider is used for dividing a reference frequency of a crystal oscillator(400) according to reference division data of the second control data. A 1/8 prescaler is used for dividing an oscillation frequency of the second local oscillator(311). A 1/N programmable divider is used for dividing the output frequency of the 1/8 prescaler into the division data of an IF2 selector(413). A phase detector is used for detecting a phase difference between the divided reference frequency divided by the I/R reference divider and the oscillation frequency divided by the 1/N programmable divider. A charge pump is used for pumping the charge corresponding the phase difference of the phase detector. A loop filter is used for filtering the voltage of the charge pump to the DC voltage.