| 摘要 |
PURPOSE:To improve the S/N and at the same time to decrease the number of elements by using two current mirrors a constant current source and a transistor to constitute a photoelectric converting amplifying circuit. CONSTITUTION:A transistor TR is connected in parallel to TRQ1 and Q2 constituting the 1st curent mirror, and an output is extracted out of the TR although an output terminal is not shown in the diagram. In other words, the base and the emitter of the TR are connected in common to the TRQ1 and Q2. Then a resistance is connected between the collector of the TR and an earth, and an output terinal can be extracted out of the collector of the TR. Otherwise an output can be extracted directly out of the base of a TRQ5. In such a constitution, it is not needed to flow an optical current produced by the steady light to a bias resistance of a conventional circuit. Thus the S/N can be greatly improvided. In addition, the number of elements can be decreased since the use of an operational amplifier is not needed.
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