Wednesday, January 28, 2015

Expansion interface: the tuning begins

I finished connecting all of the expansion nets tonight. The current route is committed on my Titan Github page. The principle trade-off was that I had to use some long traces. Figure 1 shows the current state of the route. I've also listed the minimum and maximum trace lengths for each DDR data group in Table 1. As I start tuning the trace lengths, I may re-route some nets to make the design easier to tune (both by balancing layer usage and shortening the longest routes).

Figure 1. Expansion Route (All Nets Connected, Pre-tuning).

Expansion Header P3Expansion Header P5
A_DQ0 min1239.646B_DQ0 min1718.488
A_DQ0 max3388.985B_DQ0 max2966.341
A_DQ1 min1059.547B_DQ1 min1248.02
A_DQ1 max1604.663B_DQ1 max3499.98
Table 1. Net Minimum and Maximums.

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