| 摘要 |
In an optical receiver including an avalanche photodiode (APD), a monitor circuit monitors the operating point of a preamplifier. A bias control circuit usually transfers a control signal received from an AGC (Automatic Gain Control) control circuit to an APD bias circuit. When the value being monitored by the monitor circuit exceeds a preselected level, the bias control circuit controls the APD bias circuit such that the above value coincides with the preselected level. The various sections of the receiver are free from damage ascribable to an increase in the photocurrent of the APD.
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