Photoelectric conversion circuit

Abstract

Abstract PURPOSE:To eliminate the effect of parasitic capacitance on a frequency and the effect of input capacitance by making a change in a voltage impressed across a photodetector equal and further making a voltage change at a source terminal of the 1st amplifier means equal to an input voltage change. CONSTITUTION:When a light signal is inputted to a photo diode 1, a converted current flows to a resistor R3 so as to increase the voltage of a gate G of an FET1 as the 1st amplifier to flow a current, a signal voltage is impressed to a base B of a pnp transistor (TR)1 as the 2nd amplifier and a signal output is extracted. Since the voltage gain of the photoelectric conversion circuit comprising the 1st and 2nd amplifiers is the unity, both ends of the photo diode 1 are reverse-biased by a prescribed voltage value at all times. Further, the change in the cathode voltage of a Zener diode 3 is equal to the change in the anode voltage of the photo diode 1 thereby allowing the voltage at the source S of the FET1 to be change identially to the voltage change in the gate G.

Inventors

• 👤 Akira Fukuda
• 👤 晃 福田
• 👤 Hisashi Takada
• 👤 高田　寿士

Bibliographic Details