Patent ID: 7535266
Filing Date: 2009-05-19
Classification: H01S

Abstract:
1. A light emitting device driving circuit comprising: first and second current mirror circuits each of which having a pair of parallel lines in a state, where each one side line of said parallel lines is connected via a connection node to said light emitting device; applying direct current and high-frequency current respectively to the other side lines of the line pairs in said first and second current mirror circuits, a direct current source being connected at a downstream region of the other side line of the first current mirror circuit; and supplying, through the connection node, driving current generated by superimposing high-frequency current onto direct current, wherein, there is provided an amplitude setting transistor for controlling, by using an input of reference direct current signal, the amplitude of the high-frequency current flowing through said second current mirror circuit so that a direct current component generated based on said reference direct current signal is subtracted from the direct current flowing from the direct current source in said other side line of said line pair of said first current mirror circuits, wherein the increment of the direct current component of said high-frequency current is set to be proportional to the direct current component subtracted from the direct current flowing from the direct current source in said other side line of said line pair of said first current mirror circuit.