Procedure for length matching of daisy-chained clock and command/address/control signal traces including via length compensation

High-speed DDR3 and DDR4 memory requires tight length matching between clock and data traces so that signal timing parameters can be met. In this paper, we look at the length matching between clock and command/address/control (CAC) on daisychained signal routing for memory-down DDR3 and DDR4 DRAM. We will include the compensation for the via length as the signal traces are often routed on different layers. The compensation for via length on daisy-chained traces is usually tricky and most board layouts either do not compensate or compensate wrongly.