| 摘要 |
The invention relates to a feedback loop for a laser diode driving circuit for ensuring that the laser diode generates optical power at a constant safe level. The feedback loop includes a monitor diode, which generates a monitor current Imon, and a set resistance for generating a set voltage based on the monitor current and the set resistance. The set voltage is compared with a reference voltage in an operational amplifier, which generates a control signal for controlling the laser diode current source. The laser diode current source dictates the amount of bias current transmitted to the laser diode. Safety features, in the form of voltage comparators, are provided to ensure that: a) the feedback loop is closed, i.e. Imon is not too low; b) the optical power is not above standard safety threshold, i.e. Imon is not too high; and c) the monitor diode voltage is sufficient to provide specified optical power to electrical power conversion.
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