| 摘要 |
PURPOSE:To obtain proper response characteristics in applying this ALC circuit to a transmission circuit where the transmission state is changed suddenly in a mobile radio or the like by providing an ALC voltage detecting means corresponding to individual causes and providing plural time constant circuits holding individually each ALC voltage. CONSTITUTION:When overdrive is caused in a mobile radio or the like during transmission and the 1st and 2nd ALC voltage are outputted respectively from the 1st and 2nd time constant circuits 7 and 12 because of deterioration in the SWR, a variable gain amplifier 2 is controlled according to them. Since the 2nd ALC voltage is restored in a comparatively shorter time constant than the conventional time constant when the SWR becomes normal, the variable gain amplifier 2 receives the control only at the 1st ALC voltage. When an antenna mismatching detector 10 is actuated with a transmission final stage section 3 at normal state and the 2nd ALC voltage is generated, since the 2nd ALC voltage is kept by the 2nd time constant circuit 12 having a comparatively shorter time constant, when the mismatching is cancelled, the operating characteristics of the variable gain amplifier 2 follow up it and the circuit is restored to the normal state. |
