Apparatus and method for expanding the capture range of the automatic tuning of a television receiver

摘要

The method comprises tuning a television broadcast signal to a specified channel corresponding to an external tuning voltage when a channel switching operation is performed, or the TV is powered ON. The intermediate frequency signal of the tuned signal is processed from the tuner to output an automatic fine tuning voltage and a synchronous signal. A circuit buffers the fine tuning voltage and the synchronous signal. A control circuit decreases the tuning voltage to the tuner until the automatic fine tuning voltage is higher than a predetermined reference voltage, and controls it to maintain it within a desired range between the second and third predetermined reference voltages. Pulling range of automatic fine tuning can be extended to audio band, and detuning due to variation in characteristics of components can be prevented at high or low temperature.