AGC circuit of FM front-end portion for controlling bandwidth detection sensitivity

摘要

According to this invention, there is disclosed an AGC circuit of an FM front-end portion, including an attenuator for attenuating an input signal in accordance with a level of a first signal, an amplifier for amplifying the input signal in accordance with a level of a second signal, a first input amplitude control circuit for outputting third and fourth signals in accordance with a receiving electric field strength of a receiver, a receiving electric field detecting circuit for outputting a fifth signal in accordance with an amplitude of an IF signal in the receiver, and a second input amplitude control circuit for adjusting levels of the first and second signals by changing the third and fourth signals in accordance with the fifth signal.