| 摘要 |
An optical receiver 30 having a photodetector 21, amplifier 34 feedback loop 36, 38, and output circuit 38 is disclosed. The photodetector generates a current between first and second nodes in response to being illuminated with light. The amplifier has an input connected to the first node and an output connected to a third node. The feedback path connects the third node to the first node, and includes a diode in series with a circuit element having an impedance greater than a predetermined value: the diode is connected between the first and fourth nodes. The output circuit is connected to the fourth node and provides an output signal to an external circuit. The output circuit can be configured to provide an output signal that is proportional to the logarithm of the intensity of the light that illuminates the photodetector. In one embodiment the circuit element may have an impedance for current flowing from the third node to the first node that is less than the impedance in the reverse direction. This may be achieved using a circuit element comprising two transistors (43, 44 Fig. 4). The photodetector may have a parasitic capacitance. |
