GDDR5 Data Jitter Measurement on 4 Channel Oscilloscope
Application Notes
Introduction
GDDR5 (Graphics Double Data Rate, version 5) dynamic random-access graphics card memory technology is used in high performance GPU (Graphics Processing Unit) for the mainstream mobile and gaming users. Latest GDDR5 technology offers data rates of 5 Gb/s or higher. At these high data rates, data jitter measurements are important in order to understand the effects of jitter on the data valid window. Measuring and understanding the components of jitter can enable designers to minimize jitter on the overall system design to ensure valid and accurate data transfer. Read and write data should be analyzed separately for their individual data valid windows. With GDDR5’s design of a free running data clock (WCK), small unit intervals, and minimal distinguishable skew between read and write data to WCK, identification of read and write data to make the data jitter measurement can be difficult and time consuming. This article describes new GDDR5 data jitter measurement technique using only 4 channels of high bandwidth oscilloscope.