COLORADO SPRINGS, Colo. Gennum Corp. is using technology acquired from SiGe Semiconductor in 2004 to demonstrate fully-integrated receive optical subassemblies (ROSAs) at the Optical Fibers in Communications conference later this month.
When Gennum acquired the Lightcharger line from SiGe, one benefit was the patents surrounding its Rchip, or receiver on a chip, technology, which combines a photodiode, transimpedance amp and passives on a stacked die.
Gennum will unveil a range of short- and long-wave ROSAs for 10-Gbit Ethernet and Sonet applications spanning data-center to ultra-longhaul distances. Imran Sherazi, director of marketing for optical products at Gennum, predicted the long-wave GN 3050 for 1,310-nm applications may prove the most popular since it is intended for metro-area Ethernet links up to 10 km.
Rchip was optimized to reflect Gennum's experience in manufacturing surface-mount hybrids and special video chips. The methodology reduces wirebonding between devices in the ROSA, and shows high sensitivity and gain stability as well as consistency across devices manufactured in a single lot. One advantage of the Rchip design is that it can use traditional wafer fab step-and-repeat lithography to integrate passive devices.
In contrast to ROSAs with three inductors in the AC path, Gennum's Rchip has no inductors in the AC path, allowing stable gain of approximately 20 kilohms. This can eliminate post-amplification in designs using the new SFP+ optical form factor, Sherazi said. The ROSA device uses only seven wirebonds, and no external RF capacitors.
Long-wave ROSAs use flip-chipped PIN diodes, with wafer-level test performed after PIN integration. The short-wave ROSA is wafer-tested after TIAs are integrated with decoupling capacitors.
Four ROSAs will be shown at the optical conference:
The 850-nm GN3150, a short-wave device for multimode fiber used in storage-area networks at distances of 50 to 300 meters.
The long-wave, 1,310-nm GN3050 is intended for single-mode fiber solutions out to 10 km, supporting both 10G Ethernet LR standards and OC-192 Sonet SR-1.
The long-wave 1,550-nm GN 3250 for city-to-city applications at distances out to 40 km.
The long-wave 1,310-nm GN3052 is intended for emerging long-range multimode fiber applications, and integrates automatic gain control functions to support 10G multimode performance out to 220 km.