We will be proceeding with the fifth generation of DRAM technology on phones, LPDDR5, ostensibly from early 2020. Apart from phones, LPDDR5 will also find applications in cloud computing, autonomous cars, and AR systems.
Mobile computing has become increasingly demanding and factors like industry switch to high-resolution content, high refresh rate screens, increased reliance on AI for mobile applications, and the impending transition to 5G connectivity further warrant the need for a faster and better memory. Also, RAM is quite easy to market on mobile devices, and OEMs are under constant pressure to innovate.
So, how much of an impact with the LPDDR5 have on your mobile experience? Let’s answer all LPDDR5 related questions while comparing it with the currently dominant LPDDR4x and LPDDR4 RAMs.
What is LPDDR5? How does it improve over LPDDR4x or LPDDR4?
LPDDR5 breaks down to the fifth generation of Low Power Double Data Rate technology. The standard was defined by JEDEC in February 2019, which was months after Samsung had already announced its work on LPDDR5 memory.
LPDDR5 succeeds LPDDR4x which is a power-efficient RAM technology that can be seen even on affordable phones like Redmi Note 7 Pro. The LPDDR5, however, is still expensive technology and will be available only across flagship phones in 2020.
As expected from generational advancements, the LPDDR5 brings in improved data transfer speed (up to 50%) at lower power consumption (up to 30%).
For now, only Samsung is mass producing 12GB LPDDR5 RAM using the second-generation 10nm process. The 16GB LPDDR5 memory from Samsung is also expected to hit mass production in 2020.
LPDDR4 vs LPDDR5: Power efficiency
Over the last few years, the prime focus has been on reducing power consumption. That is not to say that the data rate hasn’t improved with every successive generation.
While moving from LPDDR4 to LPDDR4x, the output VDDQ voltage – that is responsible to drive signals between RAM and your phone’s chipset – was reduced from 1.1v to 0.6v. This voltage reduction was what primarily brought in the improvements in power efficiency.
Voltages have been reduced with LPDDR4x to LPDDR5 (not the VDDQ, though), but this time the power efficiency gains are driven by many different factors and holistic design refinements. These factors include the use of variable voltage (up to 1.1V), improved clocking inspired by GDDR5 memory used in graphics cards, and – primarily – the new deep sleep mode which ensures that LPDDR5 DRAM consumes 50% lesser power in idle mode as compared to LPDDR4x.
Overall, Samsung and JEDEC claim that its LPDDR5 RAM will be up to 30% more power-efficient over LPDDR4x – which is a substantial gain.
LPDDR5 vs LPDDR4: Data rate improvements
Now let’s come to speed.
TL;DR: Samsung’s 12GB RAM will have a 44GB/s bandwidth of 5500 Megatransfers per second (MT/s) data transfer rate which is about 30% higher than LPDDR4x memory (4266 MT/s). Samsung is working on 16GB LPDDR5 chips that will have a higher 6400 MT/s data rate or around 50% improvement over LPDDR4x as was listed in JEDEC definition.
So, how does LPDDR5 achieve this improved speed?
If you remember, the LPDDR4 and LPDDR4x got a speed boost by adopting a 32bit dual-channel architecture (2 x 16 bit). With the LPDDR5, we have switched back to a single 16-bit channel, but the number of banks in each channel has been doubled from 8 to 16.
DRAM Memory speeds are a lot slower than our processors and a technique that helps them compensate is the use of prefetch buffer. Increasing the size of the prefetch buffer has been an easy way to improve DRAM performance.
Samsung’s LPDDR5 memory uses the same 16bit prefetch buffer as LPDDR4. For improvement in data rate, LPDDR5 relies on something called bank grouping (which is also what DDR4 DRAM uses). The cadence video below lucidly explains bank grouping basics.
Which chipsets support LPDDR5 RAM?
The LPDDR5 RAM is still considered an expensive memory and the support is quite limited. As of now, Samsung 990 is the only chipset that supports LPDDR5 memory. Upcoming Snapdragon 865 is expected to integrate LPDDR5 support as well.
Huawei’s latest Kirin 990 does not support LPDDR5.
When will we see LPDDR5 on Phones?
Samsung Galaxy S11 that’s due for arrival in Q1 2019 is expected to be the first phone to include LPDDR5 RAM. We also expect the next generation of iPhones to employ the next generation RAM.