| 摘要 |
PURPOSE:To reduce electric poewer consumption without making a mutual modulation product worse by controlling collector current by supervising an output level. CONSTITUTION:A radio wave from a base station is received by antenna 21 and, after being amplified by linear amplifier 22 to a constant gain, is supplied to antenna 23 at the output side. Part of the output is detected by detecting circuit 24, whose output is compared to a reference level by comparing circuit 25; and the bias value of bias circuit 26 connected between the emitter and base of the transistor of linear amplifier 22 is continuously varied by the output of the comparing circuit to control the collector current so that the mutual modulation product will not increase. While the gain of linear amplifier 22 is made constant, the cross modulation product can be maintained and the circuit can also be operated with irreducible required current consumption. |
