This paper describes a quad optical transceiver for low-power high-densityshort-distance optical data communication. Each channel transmits10 Gb/s over a multimode (MM) fiber and features a link margin of5.2 dB at a bit error rate (BER) of 10/sup -12/. The transmit andreceive amplifying circuits are implemented in an 80-nm digital CMOSprocess. Each driver consumes 2 mW from a 0.8-V supply, and eachvertical cavity surface-emitting laser (VCSEL) requires 7 mA froma 2.4-V supply. The receiver excluding the output buffer consumes6 mW from a 1.1-V supply per channel and achieves a transimpedancegain of 80.1 dB/spl Omega/. The isolation to the neighboring channelsis >30dB including the bond wires and optical components. A detailedlink budget analysis takes the relevant system impairments as lossesand power penalties into account, derives the specifications forthe electrical circuits, and accurately predicts the link performance.This work presents the highest serial data rate for CMOS transceiverarrays and the lowest power consumption per data rate reported todate.