US Patent 7406018 Signal generating circuit and optical pickup device provided therewith

A signal generating circuit of the invention includes a current polarity switch circuit that receives an output current of a light-sensitive element and outputs a current of which the direction the polarity switch circuit keeps constant regardless of the direction of the received current, a current-to-voltage conversion circuit that converts the current outputted from the current polarity switch circuit into a voltage, and a signal processing circuit that receives the voltage outputted from the current-voltage conversion circuit to generate a signal based on the received voltage. Thus, the signal based on the received current signal can be generated regardless of the direction of the received current signal.