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Abstract

An optical data signaling apparatus includes a trans-impedance amplifier for receiving a data signal current produced by a sensing photodiode in response to an optical data signal and an ambient current produced by a dark photodiode. Preferably, the dark photodiode has the same performance and manufacturing characteristics as the photodiode sensing the optical data signal, but is masked from receiving any light. The trans-impedance amplifier is configured to receive the ambient current from the dark photodiode as a first differential input and the data signal current from the sensing photodiode as a second differential input, the first differential input thus serving to cancel noise and environmental effects of the photodiodes, and allowing the amplifier to produce a stable and accurate differential voltage in response to the data signal current. An optical data signaling method includes receiving a data signal current produced by a sensing photodiode in response to an optical data signal, receiving an ambient current produced by a dark photodiode, using the ambient current as a differential reference for the data signal current, and producing a stable differential voltage in response to the data signal current by cancelling effects of noise and environmental factors represented by the ambient current.

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