Threshold adjustment compensation of asymmetrical optical noise

An optical communication system comprising:

• an optical-to-electrical conversion circuit configured to produce first and second differential electrical data signals, at respective first and second electrical nodes, in response to a single-ended optical data signal;
• a termination circuit coupled to the first and second electrical nodes;
• a first digital-to-analog converter (DAC) circuit coupled to the first electrical node, the first DAC circuit comprising a first binary input and a first voltage output;
• a second DAC circuit coupled to the second electrical node, the second DAC circuit comprising a second binary input and a second voltage output;
• and
• a linear equalizer circuit coupled to the termination circuit and the first and second DAC circuits;
• and
• wherein the first and second DAC circuits are configured to adjust the first and second differential electrical data signals based on the respective first and second voltage outputs such that a zero-crossing point of a positive data signal is pulled up and a zero-crossing point of a negative data signal is pulled down.

A method for threshold adjustment compensation of optical noise when generating electrical data signals from an optical data signal, the method comprising:

• converting the optical data signal to first and second differential electrical data signals;
• generating first and second threshold adjust signals based on a default code and circuit characteristics;
• adjusting a zero-crossing point of the first and second differential data signals based on the respective first and second threshold adjust signals such that the zero-crossing point of positive data is pulled up and the zero-crossing point of negative data is pulled down;
• and
• equalizing the first and second differential data signals after the zero-crossing points of each signal has been adjusted to generate the electrical data signals.