March 26, 2007 – IBM says it has developed a prototype optical transceiver chipset for supercomputing applications that incorporates optical and CMOS components in one system-in-package (SiP).

The single-chip CMOS optical transceiver was built using IBM’s 0.13-micron CMOS process with eight metal layers, and 16 independent laser-diode driver and 16 receiver amplifier ICs arrayed in separate 4 x 4 blocks, coupled with other optical components (e.g. InP and GaAs devices) into a 3.25mm x 5.25mm package. The 16 10Gb/sec transmitter and receiver channels combine for a 160 Gb/sec aggregate bit rate, consuming 15.6 mW/Gb/sec with an area efficiency of 9.4 Gb/sec/mm² per link. That translates into 8x faster speeds than conventional optical components, and fast enough to download typical high-def feature films in just one second, the company said in a paper presented at the 2007 Optical Fiber Conference.

Researchers use photodiode array and laser array flip chips with driver and receiver ICs to reduce the bulk of an optics module for the prototype transceiver. Conventional methods of packaging, wafer fabrication, and assembly make the chipset economically viable, said Marc Taubenblatt, senior manager, and Clint Schow, research staff member, from IBM’s TJ Watson Research Center in Yorktown Heights, NY. Integration allows the chipset to transfer data at 160 Gbits speeds. The density of connections and high number of channels enhance chip performance, they noted.

Thermal concerns are addressed in package design, and gold/tin (Au/Sn) solder microbumps are used for the flip chip bonds. Post-assembly, the SiP can be tested with probe techniques; channels are readily accessible, according to the researchers. This technology could be integrated with PCBs