LOW-NOISE LASER DRIVING CIRCUIT AND AN OPTICAL PICKUP CIRCUIT CAPABLE OF USING THE DRIVING CIRCUIT, SPECIFICALLY CONCERNED IN REDUCING THE INFLUENCE OF AN EMI NOISE WHILE REALIZING CIRCUIT MINIATURIZATION

摘要

PURPOSE: A low-noise laser driving circuit and an optical pickup circuit capable of using the driving circuit are provided to install a ferrite bead or a condenser on a path of a driving current to reduce influence of an EMI(Electromagnetic Interference) noise, thereby accomplishing miniaturization of an optical pickup. CONSTITUTION: A laser beam of a laser diode(LD) is detected by a photo detector(PD), and a detection signal is transmitted to a main substrate(61). An APC circuit(65) of the main substrate(61) outputs a control signal for regularly controlling a laser beam output of the laser diode(LD) according to the detection signal. A laser driving circuit(63) included in an optical pickup circuit(62) is embedded with a transistor(Tr) and an RF overlapping circuit(64). The transistor(Tr) creates a driving current according to the control signal, while the RF overlapping circuit(64) overlaps the driving current with an RF current. The laser diode(LD) is driven by the driving current overlapped with the RF current.