| 摘要 |
PROBLEM TO BE SOLVED: To provide an automatic gain controller which is reduced in a delay in a feedback control loop while a data error rate is suppressed, is small in the variation in an output power of a gain variable amplifier with respect to variation in circuit elements , and is low in manufacturing cost. SOLUTION: A control voltage switching circuit 31 compares a control voltage of the variable gain amplifier 2 by a feedforward control loop 21 with a control voltage of the variable gain amplifier 2 by a feedback control loop 6 for a period t, applies feedforward control to an output of the variable gain amplifier 2 by the feedforward control loop 21 when a difference between the control voltages is a preset value or over, and applies feedback control to the output of the variable gain amplifier 2 by the feedback control loop 6 when a difference between the control voltages is less than the preset value. COPYRIGHT: (C)2008,JPO&INPIT
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