Jitter generation and measurement for test of multi-Gbps serial IO

摘要

The advent of serial communication links in chip-to-chip and system-to-system applications has resulted in intense focus on jitter and BER testing techniques, including jitter generation and measurement methodologies. We describe techniques for injection of random and deterministic jitter in controlled and programmable fashion, including a novel data-dependent jitter (DDJ) generation method that eliminates the need for bulky and difficult-to-control DDJ injection filters. These techniques can be employed for a wide range of applications with different bit rates and patterns in a single setup. We also introduce the concept of continuous time interval analyzer (CTIA) and demonstrate how it can be used for fast and accurate jitter measurement without any trigger signal. Subsequently, we present jitter measurement methodologies and results using the real-time and equivalent-time sampling oscilloscopes, which are used as benchmarks for verification of the CTIA measurement accuracy.