Photoelectric current and voltage converting circuit

摘要

A photoelectric current and voltage converting circuit converts a photo current Ipd generated by the input to photo diode into a voltage Va by a feedback resistor connected to an inverting input and an output of an amplifier, and compares the output voltage Va with a threshold voltage Vth from a reference voltage circuit to output a binary signal. Divided voltage Vb gained from a connecting node of the feedback resistors is inputted to a non-inverting input of the reference voltage circuit and is offset to a higher voltage by Vos to generate a threshold voltage Vth. As a result, the threshold voltage Vth can be supplied which impedance is low and robust to noise, and errors of the comparator or jitter of the output of the comparator are suppressed.