| 摘要 |
PURPOSE:To prevent an output voltage from being affected by temperature and power supply voltage by connecting a current-voltage conversion preamplifier circuit to a photodetector and connecting a main amplifier circuit to the preamplifier circuit via a resistor. CONSTITUTION:The current-voltage converting preamplifier circuit 1 feeds back an output of a transistor (TR)Q2 to an input side of a TR circuit via a resistor R1. Similarly, an output of a TRQ7 is fed back to the input of a TRQ6 via a resistor R4 in a main amplifier circuit 2. The preamplifier circuit 1 and the main amplifier circuit 2 are connected via a resistor R3. A reference voltage generating circuit 3 decides the operating current of TRs Q5, Q10. In setting the value of resistors R1, R3, R5 and R7 so as to establish the relation of R3R7=R1R5 and selecting the ratio of the resistor R3 to the R4 to a prescribed value, the output voltage is made independent of the temperature and power voltage. |
