| 摘要 |
PURPOSE:To lower a source voltage by adding a level shift circuit consisting basically of an npn transistor (TR) and a pnp TR on multiple connection basis to the output circuit of a high-input-impedance operational amplifier. CONSTITUTION:A photoelectric converting element such as a photodiode and a phototransistor is used, and an electric signal obtained by the conversion of the photoelectric converting element Q1 is amplified by the high-input-impedance operational amplifier 100. On the other hand, feedback diodes Q2 and Q2' compress a photocurrent logarithmically and the logarithmically compressed voltage is measured. At this time, the level shifting circuit 200 consisting of the emitter- follower npn TR and the emitter-follower pnp TR on multiple connection basis is used as the output circuit of the operational amplifier 100. |
