| 摘要 |
PROBLEM TO BE SOLVED: To evade the occurrence of any distortion or noise in an output signal when any of parallel amplifiers breaks down in an automatic gain controller into which parallel amplifiers are integrated due to the increase of the input signal levels of the other amplifiers or the amplification in a non-linear region. SOLUTION: A number of failure detecting circuit 11 detects a number X of the failure of parallel amplifiers 41 to 4N, and a reference voltage generating circuit 12 supplies preliminarily set reference voltages Vm0 to VmN to a control signal generating circuit 9 based on the detected number X. Therefore, even when the output is largely lowered due to the failure of the parallel amplifiers 41 to 4N, the control signal generating circuit 9 receives the reference voltages Vm0 to VmN whose reference level is different corresponding to this, and derives a control signal S. Thus, the sharp increase of the input signal level in the normal parallel amplifier can be reduced, the occurrence of any distortion or noise can be evaded, and the output signal whose characteristics are satisfactory can be successively transmitted. |
