Optical receiver

An optical receiver comprising:

• a signal process circuit that carries out an output process of data received by a light sensing device;
• an activation control circuit, (a) for determining, based upon a level of a voltage of a low-frequency current component of a current signal generated by the light sensing device, whether or not data is being received, and (b) for outputting a signal C, which, when data is being received, is a signal CA indicating that data is being received, so that the output of the signal CA activates the signal process circuit, and when no data is being received, is a signal CB indicating that no data is being received;
• an operation determining circuit for determining, based upon a level of an output signal of the signal process circuit, whether or not data is being received, and outputs a signal G which, when data is being received, is a signal GA indicating that data is being received and when no data is being received, is a signal GB indicating that no data is being received;
• a control signal output circuit for outputting a control signal according to comparison between a predetermined boundary value TH and a determination signal that the control signal output circuit generates, the control signal being such that at least in a period in which the signal C is CA, the control signal is an ON signal if the comparison shows that a direction from the boundary value TH to the determining signal currently generated is a direction D1, or is an OFF signal if the comparison shows that the direction from the boundary value TH to the determining signal currently generated is a direction D2, where the direction D1 is one of an increasing direction and a decreasing direction and the direction D2 is the other one of the increasing direction and the decreasing direction, and where (a) if in the period in which the signal C is CA, a first change occurs that is a change of the signal G from GB to GA, the determination signal changes a level thereof in the direction D1 at such a level change rate that the level of the determination signal is changed at least beyond the boundary value TH within the period in which the signal C is CA, (b) if a second change occurs that is a change of the signal G from GA to GB after the first change, the determination signal changes the level thereof, at least within the period in which the signal C is CA, in the direction D1 if the signal G is GA or in the direction D2 if the signal G is GB, but the determination signal changes the level thereof at such a level change rate that the level of the determination signal is changed not beyond the boundary value TH within the period in which the signal C is CA, and (c) after the second change, the determination signal changes the level thereof so that the level of the determination signal is beyond the boundary value TH after the signal C changes from CA to CB;
• and
• an output control circuit for switching, according to the control signal from the control signal output circuit, whether or not the optical receiver outputs an output signal of the signal process circuit therefrom.