| 摘要 |
PROBLEM TO BE SOLVED: To extend the dynamic range by providing a low pass filter circuit, an emitter follower and a feedback resistor so as to improve a high input withstanding characteristic without deteriorating the sensitivity. SOLUTION: A low pass filter circuit LPF passing through only a DC component being an offset component of an output voltage is provided to an output of an inverting amplifier AMP being a transistor(TR) circuit. Then a 2nd feedback resistor 7 is provided, which is substantially connected in parallel with a 1st feedback resistor 6, and its resistance is selected lower than the resistance of the 1st feedback resistor 6 for the DC component passing through the low pass filter LPF thereby increasing the upper limit at which the AC component of an output voltage is able to be reached. Even in the case of the operation at a higher light receiving level, the output current does not reach the upper limit, there is no distortion in an output waveform of an output voltage resulting from the inversion and amplification of the output current by the inverting voltage amplifier AMP and outputted from an output terminal 2A and then no deterioration is caused in the duty factor. |
