| 摘要 |
PROBLEM TO BE SOLVED: To realize the stable operation of a circuit by preventing noises or oscillation generated in a power line in the circuit, in which a plurality of amplifiers are connected longitudinally. SOLUTION: The power line of an amplifier 1 at a first stage for dealing with a minute signal is isolated from the power line of the other amplifiers 2 and 3, and the respected power lines 4 and 8 which are isolated are connected to a common power supply pad 6, thereby preventing large potential difference from generating between the amplifier 1 and the amplifiers 2 and 3, due to current difference drawn into the respective amplifiers 1-3, and preventing noises due to potential difference. Also, the feedback loop of the amplifier 1 is made different from those of the amplifiers 2 and 3, to prevent a drawback that a large signal feeds back from the amplifiers 2 and 2 at the latter stages back to the amplifier 1 at the first stage.
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