| 摘要 |
PURPOSE:To correct temperature characteristics through simple constitution, by generating a correcting voltage on the basis of the difference between the sum of a voltage corresponding to a current proportional to absolute temperature and the reverse saturation current (Is) of a diode and a voltage corresponding to a current with a temperature coefficient and the Is, and a voltage proportional to the absolute temperature. CONSTITUTION:A voltage generating circuit 11 supplies voltages Vo and Vo' proportional to the absolute temperature to the uninverted input terminals of OP amplifiers 2 and 3. The inverted input terminal of the OP amplifier 2 is connected between a resistance R1 and the collector of a transistor (TR) Q1, a photodiode D1 which photodetects light transmitted through a lens is connected between the inverted and uninverted input terminals of the operational amplifier 3, and a log diode D2 is connected to a negative feedback loop. An arithmetic circuit 4 outputs the difference V3 between a voltage V2 corresponding to the reverse saturation current Is of TRs Q1-Q3 and a current proportional to the absolute temperature and an output voltage V3 having the temperature coefficient of the OP amplifier 3, and a comparator 6 compares it with a reference value 5 proportional to the absolute temperature to obtain the correcting voltage for temperature characteristics. |
