| 摘要 |
PURPOSE:To reduce a charge per stage in an optical output and to enhance control accuracy of the optical output by providing the following: an electric-current detection circuit used to detect an electric current of an electric-current source; a bias addition circuit which is operated by an output of the circuit and which additionally generates a definite electric current at the electric-current source separately from the electric current from a bias circuit. CONSTITUTION:In a laser diode control circuit which contains a laser diode 1, an electric- current source used to generate an optical output at the laser diode 1; a bias circuit 5 used to generate a definite electric current at the electric-current source and variable electric-current circuits 7, 6 used to generate a quantumwise variable electric current at the electric-current source, an electric-current detection circuit 12 used to detect an electric current of said electric- current source and a bias addition circuit 17 which is operated by an output of the electric- current detection circuit 12 and which can additionally generate a definite electric current at the electric-current source separately from that of said bias circuit 5 are provided. For example, the following are provided: an electric-current detection circuit 12 used to detect whether a forward current IF flowing at a resistor R9 is more than a definite value or not; a latch circuit 13 equipped with a reset function and used to latch a signal of the electric- current detection circuit 12; a delay circuit 14; one-shot circuits 15, 16; a bias addition circuit 17 and the like. |
