| 摘要 |
PURPOSE:To make it difficult to receive the noise from the external to improve S/N by joining a preamplifier circuit with a photodetector into one body and integrating them with a bipolar IC to smoothly slide an optical pickup itself. CONSTITUTION:A P-type substrate 40 is the common anode of a light detecting part, and n<-> epitaxial layers 41-44 are cathodes of the light detecting part and correspond to six divided photodetectors E, A or B, D or C, and F in order from the left. What is called a bipolar transistor is constituted with each of combinations among an n<-> epitaxial layer 45, a P diffused layer 53, and an n<-> diffused layer 56 and among P diffused layers 54 and 55 and an n<-> epitaxial layer 46 through N type and P type are inverted. When the output of a semiconductor laser is projected to light detecting parts 41-44, a photocurrent is inputted to a current-voltage conversion amplifier formed on the same substrate by an Al wiring about 1mm long and is amplified there and is supplied to another electronic circuit substrate through a lead wire.
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