A novel multifunctional transceiver for chip-to-chip optical interconnects operating at 2.5 Gbit/s is proposed which shares a common block between a receiver and a transmitter. This transceiver provides four conversion functions - electrical-to-optical, optical-to-optical, optical-to-electrical, and electrical-to-electrical - depending on the selection switch on a single chip. The whole chip integrated in 0.18 mu m CMOS occupies an area measuring 0.82 x 0.82 mm(2).