Data receiver

摘要

A data communication receiver that provides very low pulse distortion at excellent sensitivity over a wide range of optical signal levels and simplified circuitry for the detection of data collisions. The receiver comprises an amplifier having a series of stages, all but one of which is directly coupled to the preceding stage and one of which is capacitively coupled by a capacitor that also functions as part of an RC differentiator. The output of the amplifier is a series of peak signals that are applied to a Schmitt trigger, the output of which is applied to a collision detection circuit. In a preferred embodiment of the invention, the collision detection circuit comprises a timing circuit for producing an output signal for a period of time equal to the longest interval during which a received data signal can have a first polarity and means for comparing the timing output signal with the received data signal and for producing a collision detection signal when the received data signal fails to change within the duration of the output signal from the timing means. To ensure that the Schmitt trigger produces an initial output representative of the absence of a signal in the communication medium, the amplifier is biased so that the initial output of the Schmitt trigger is low.