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SANTA CLARA, Calif.—In the long and storied history of semiconductor memories, the path to the next generation has usually been predictable, paved by density improvements and cost reduction for the PC market.
But when it comes to double data rate (DDR) memory, historical precedent is about to get turned on its head. For likely the first time, a low-power variant, in this case LPDDR4, will supplant conventional DDR as the high-volume memory choice, because it should have an edge on power, performance, and price over mainstream, PC-driven DDR memories.
That was the message from Kevin Yee (pictured, right), Cadence product marketing director, who presented at MemCon here in October.
“The bottom line is that by next year, the performance of LPDDR4 will exceed what we have on the market for DDR4,” Yee told his audience. “So you'll get better performance and significantly lower power. The question is, if I can get the performance and I can get the low power, why would I use DDR4 for a lot of applications?”
Even so, Yee was careful to note that PC DDR4 will remain the clear choice for certain high-density applications that LPDDR won’t be able to match.
What’s driving this unique transition? Mobile devices. In the mobile space, the need for performance is key but the global volumes are driving down price, Yee said. Apple can sell 5 million phones in a weekend; Xiaomi in China, which didn’t exist as a company three years ago, sold 26 million smart phones in the first half of 2014, Yee said.
"This is just another example of how dynamic this market is and how quickly volumes can ramp,” Yee said.
Phones and tablets with higher-resolution and larger displays are pushing the performance requirements, he noted. Displays are moving from 1280x720 to 3840x2160 (ultra-high definition) and beyond.
“Now you see the need for bandwidth, for density and for performance” in mobile devices, Yee said.
Volume, of course, is what drives down semiconductor pricing, but the performance improvements in LP DDR have been astonishing in recent years.
PC DDR4 bandwidth is 2133Mbs, moving to 3200, but LPDDR4 has gone to 3200 and is headed quickly to 4266.
“We’ve gone from 400Mbs to 4266 in seven years” in LP DDR, Yee noted. “As the PC market changed, we saw that transition over three decades. We’re seeing this happen (in the mobile space) in one decade in terms of where low-power memory is going.”
With higher volumes of the mobile markets, the cost premium between LP DDR and PC DDR is shrinking.
Yee noted that, in 2012, there was a 62% premium between DDR3L and LP DDR. That dropped by half with LP DDR2 (see chart left). It's early with respect to these dynamics for LPDDR4 but some companies anticipate a similar premium decrease once volumes ramp, Yee said.
“Going forward, there will be little or no premium for low power,” Yee said.
- DDR4 Roadmaps and Strategic IP Planning
- Whiteboard Wednesdays—Consumer DRAM Trends
- DDR4 in 16nm FinFET: Future-Proof Your SoC Design