| 摘要 |
PROBLEM TO BE SOLVED: To realize a photo diode amplifier circuit as a one-chip component in which a sufficient band width is reserved, the S/N is improved, at least circuits connecting to each cathode of each photo diode are designed as common circuits, DC amplification is attained, and peripheral components as many as possible are included. SOLUTION: An output voltage V1 (V11 ) that is obtained through current- voltage conversion at an operational amplifier OP 1 resulting from a current i2 (i12 ) obtained by amplifying an output current i1 (i11 ) of a photo diode PD 1 (PD 11) in response to an emitter area ratio N of a current mirror CM 1 (CM 11) by a multiple of N, is fed to a differential amplifier OP 3, from which a differential output voltage Vo . Thus, only a signal component level of the differential output voltage Vo is multiplied by a multiple of N through the setting of the emitter area ratio N of the current mirror CM 1 and then the S/N is improved by the multiple. |
