Description

If you have ever worked with communications, data centers, or enterprise networking equipment—routers, switches, server chassis—you probably have heard the term green-box test. A green-box (GB) test applies to multi-gigabit serial links and is a procedure that seeks to identify the optimum transmitter equalization settings by sweeping these parameters and measuring a corresponding figure of merit (FoM). For systems with hundreds or thousands of high-speed channels, GB testing is often the most reliable way to pinpoint the transmitter settings which enable the system to meet the required bit error rate (BER). This article describes the GB test methodology and its applications.