Patent ID: 7729399
Filing Date: 2010-06-01
Classification: H01S

Abstract:
1. A semiconductor laser driving circuit configured to perform at least a first operation to convert a laser light emitted from a semiconductor laser into a first electrical current by a light receiving element; a second operation to control a second electrical current supplied to said semiconductor laser such that a first voltage corresponding to said first electrical current reaches a predetermined voltage; and a third operation to drive said semiconductor laser by controlling said first voltage such that a first light intensity reaches a predetermined light intensity, a single integrated circuit comprising the semiconductor laser driving circuit, said integrated circuit comprising: an amplifier circuit configured to amplify a voltage difference between said first voltage and a light intensity setting signal inputted from outside for setting a second light intensity of said semiconductor laser, said amplifier circuit comprising: a sample hold circuit configured to hold a first output voltage from said amplifier circuit according to a first control signal inputted from outside; a voltage-to-current converter, configured to convert a second output voltage from said sample hold circuit into a third electrical current, connected to an internal ground of said integrated circuit; and a switching circuit configured to perform a supply control of said third electrical current to said semiconductor laser according to a second control signal inputted from outside, wherein said sample hold circuit comprises a capacitor, connected to said internal ground, configured to hold a fourth electrical current charged by a third output voltage outputted from said amplifier circuit, wherein said amplifier circuit adjusts a charging time of said capacitor according to a preset value and a response speed of a feedback control loop of said laser driving circuit, and wherein said integrated circuit has an external terminal for connection to an external ground.