Do's and don'ts with the agilent's G-link chipset

The Agilent's G-Link serializers-deserializers are long lasting and widely used devices to implement serial links in the range of similar to 1 Gbit/s on copper and fibres. They feature a wide clocking window spanning the 13-70 MHz range, the ability to compensate for a constant phase delay in the clock distribution between the Tx and Rx node, low and deterministic link latency. All that makes this old-fashioned, power-hungry bipolar chipset still a popular choice in the design of modern trigger and data acquisition systems. The last entry in the family, named HDMP-103xA, has been released in the second half of 2001, as a drop-in replacement for the previous HDMP-103x silicon version. Despite the recent upgrade, the latest G-Link chip-set still suffers from subtle misbehaviors and undocumented bugs which may jeopardize even a very conservative design. In this paper we report our experience with G-Link during the design and test of the optical link for Level-1 Muon Trigger of the ATLAS experiment. We describe an ad-hoc platform developed for debugging the link and present the results of tests conducted in the lab.