Design of a transversal equalizer for electronic dispersion compensation in optical communication links

A programmable transversal equalizer for electronic dispersion compensation (EDC) in optical fiber communication systems is developed. Based on the SiGe technology with a cut-off frequency of 80 GHz, the equalizer consists of 6 seriesparallel amplifiers as delay units and 7 Gilbert variable gain amplifiers as taps, which ensure that the equalizer can work at the bit rate of 10 Gb/s. With different tap gains, the forward voltage gain of the transversal equalizer varies, which demonstrates that the equalizer has various filtering characteristics such as low pass filtering, band pass filtering, band reject filtering, and notch filtering, so it can effectively simulate the inverse transfer function of dispersive channels in optical communications, and can be used for compensating the inter-symbol interference and other nonlinear problems caused by dispersion. The equalizer (including pads) occupies an area of 0.40 mm×1.08 mm, and its total power dissipation is 400 mW with 3.3 V power supply.