| 摘要 |
PURPOSE:To realize the transmission output automatic control circuit compensating transmission power fluctuation automatically due to a change in an ambient temperature, a transmission frequency and a power supply voltage. CONSTITUTION:A transmission carrier 100 is modulated at a modulation circuit 1 by input base band signals 101, 102 and its output 103 is controlled at variable attenuators 2, 3, 4 by external control signals 104, CONT2 and SEL1. Part of an output 107 of a power amplifier 5 of a succeeding stage is branched by a coupler 6 and used to provide an attenuation based on the external control signals SEL2, CONT2 through variable attenuators 8, 9, its output 110 is detected by a detector 10 and an envelope is integrated succeedingly by a low pass filter 11 and its output 112 is compared with a reference DC voltage 114 at a comparator 13. A control signal 104 controls the variable attenuator 2. The direction of a change in the attenuation by the variable attenuators 3, 4 and 8, 9 provide the effect opposite to each other and a change in an ambient temperature, a transmission frequency and a power supply voltage is automatically controlled to each circuit. |
