Patent ID: 8705982

Claim:
A digital filter for processing an input signal to be conveyed through an optical communications system, the input signal comprising a serial sample stream having a sample period of T, the processing for generating a predistorted signal using a compensation function that mitigates impairments of the optical communications system, the predistorted signal comprising a serial sample stream having a sample period of T/2, the digital filter comprising: a first branch including a respective first T-spaced filter for processing the input signal using the compensation function to generate a corresponding first output signal comprising nT/2 samples with n odd; a second branch comprising a respective second T-spaced filter for processing the input signal with a delay of T relative to the first branch using the compensation function to generate a corresponding second output signal comprising nT/2 samples with n even; and a combiner for combining the first and second output signals to generate the predistorted signal having a sample period of T/2.