| 摘要 |
In a conventional light amplifier, when an addition or subtraction operation is performed on currents output from a plurality of light-receiving elements to output a voltage amplified according to the current resulting from the addition or subtraction operation, increasing the gain results in reducing the loop gain, making it impossible to achieve a wide band width. A light amplifier of the invention is provided with a plurality of light amplifier circuits, each having a light-receiving element that outputs a current according to the intensity of light received and a current amplifier that outputs a current by amplifying the output current of the light-receiving element, and a first transimpedance amplifier whose input terminal is connected to the node at which the output terminals of the individual current amplifiers are connected together. This helps prevent the lowering of the loop gain when the gain is increased.
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