A Novel Analog Decision-Feedback Equalizer for 10-Gb/sec Multi-Mode Fiber Dispersion Compensation

A novel analog decision-feedback equalizer (ADFE) is presented to compensate for modal dispersion in multi-mode fibers. The unclocked continuous-time technique and circuit architecture aims to overcome the first feedback-loop latency challenge in conventional digital or mixed-signal DFEs. An ADFE employing a 4-tap forward filter and a 1-tap feedback filter is fabricated in a 0.18-mum CMOS process. The chip with pads occupies 1.04 mm² and draws 240 mA DC current from a 1.8 V supply at a typical process corner. The circuit consumes significantly less area and power than a digital or mixed-signal approach and is used to equalize 300 meters of MMF at 10-Gb/sec.