| 摘要 |
PURPOSE: Disclosed is a semiconductor integrated circuit provided with a high frequency current generating circuit in which amplitude of a high frequency current superimposing on a control current of a semiconductor laser can be enlarged while suppressing power consumption and heat generation is less. CONSTITUTION: A semiconductor integrated circuit comprises a high frequency current generating circuit(10) generating a high frequency current superimposed on a control current output from a light quantity control circuit(4) for controlling light quantity and supplied to a semiconductor laser(1) as a drive current. The high frequency current generating circuit(10) has a current discharging type current source(21), a current absorbing type current source(22), current switches(23,24) connected respectively between the current sources(21,22) and a drive output terminal(20), a gated oscillation circuit(17) oscillating with a desired frequency, switch drive circuits(25-27) controlling complementarily ON/ OFF of the current switches(23,24) by a switch drive signal in which a high frequency component of an output signal of the oscillation circuit(17) is eliminated.
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