| 摘要 |
PROBLEM TO BE SOLVED: To provide an automatic gain control circuit in a television receiver with excellent transient response by preventing a video detection output from being distorted or being a faulty image such as a noise in a transient state caused at channel selection switching or the like. SOLUTION: A discrimination circuit 39 discriminates a state that a signal received by a turner circuit or a gain variable amplifier circuit 22 is suddenly changed, an AGC time constant (only a capacitor 35 or a parallel configuration consisting of capacitors 35, 37) of an AGC circuit 29 is switched on the basis of a discrimination output from the circuit 39. Thus, the AGC can trace a transient state caused at channel selection switching or the like or a sudden change state of antenna input electric field or the like so that the television receiver can always display an image with small disturbance. |
