Photo-receiving amplifier element, optical pickup unit, and optical disk device

摘要

A feedback resistor of a feedback circuit included in a photo-receiving amplifier element is formed on an island region in which an electric potential is in a floating state. The island region is electrically isolated from an island region on which an element other than the feedback resistor is formed. This enables the response speed of the photo-receiving amplifier element to be increased without changing the process of the circuit or varying a resistance value of the feedback resistor in a first-stage amplifier unit.