| 摘要 |
PURPOSE:To prevent the deterioration in an SN ratio accompanied by negative feedback and to improve the distortion characteristics in a light emitting element, in an optical negative feedback circuit in a photoelectric conversion device, by providing a distortion compensating means on the input side of a driving transistor. CONSTITUTION:An input signal (a) drives a driving transistor 2 through an amplifier 3. A light emitting element 1 emits light in correspondence with a driving current, and a light output (b) is generated. Part of the light output is inputted to a light receiving element 5. The received signal passes through an amplifier 6 and a bandpass filter 7. The component at the outside of the band of the main signal is taken out. A level detector 8 generates a DC output. A signal, which is obtained by dividing the voltage of the input signal, is always given to an FET 10 as a gate voltage through a resistance voltage divider 11. Therefore constant distortion is imparted to the input signal. The output of a comparator 9 is superimposed on the signal from the resistance voltage divider 11 and the result is added to the FET 10 as the gate voltage. Then the amount of the distortion generation in the input signal is increased. Thus the generation of the distortion in the light emitting element 1 is decreased by compensation. |
