PHOTO DETECTING ELEMENT, AND OPTICAL PICK-UP DEVICE AND DISC DRIVE ADOPTING THE ELEMENT

摘要

PURPOSE: A photo detecting element, an optical pick-up device, and an optical disc drive adopting thereof are provided to omit a resistor by an external additional component by forming a nonlinear multi-step resistor for a gain control inside a photo detection element integrally. CONSTITUTION: An amplification unit amplifies a signal of an optical sensor. The amplification unit comprises a first AMP (332) connected to the optical sensor and a second AMP (333) amplifying an output of the first AMP. A non-linear multi-step variable resistor (VR1-VR3) controls an output gain of the first AMP between the first AMP and the second AMP, and is operated by an external signal. The non-linear multi-step variable resistor comprises multiple fixed resistors (R1-R9) and selector switches (SW3-SW5). The selector switch selects any one among the multiple fixed resistors by the external signal.