| 摘要 |
PROBLEM TO BE SOLVED: To stably and highly accurately calculate the gain of a variable gain amplifier device used to fetch an analog signal of servo control or the like. SOLUTION: This variable gain amplifier device is newly provided with an input 9 for measurement. As a first step, the switch S2 of a switch group 6 is turned on, switches S1 and S3 to S5 are individually turned off and the gain G1 of a variable attenuator 3 seen from the input 1 is calculated. As a second step, the switch S4 is turned on, the switches S1 to S3 and S5 are individually turned off and the gain G2 of the attenuator 3 seen from the terminal 9 for measurement is calculated. As a third step, the gain of the attenuator 3 when the switch S4 is turned on and the switches S1 to S3 and S5 are individually turned off is calculated by adding the gains G1 and G2.
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