Everything You Need To Know About Mobile Phone RAM Types

Mobile RAM types

When purchasing a smartphone, all people care about is the capacity of the memory or RAM. Whether it’s 6 GB, 12 GB, or 16 GB. However, there is more to understanding RAM for mobile phones today.

The Random Access Memory (RAM) is a volatile memory, which means that it constantly needs power to retain its data, and if the power is lost, so is all of its data. Most of the operations are executed in this memory, and the apps and programs are loaded to run on the device. Therefore, the RAM’s performance significantly impacts the User Experience (UX) and hence, the phone’s overall performance.

With the evolution of phones and other gadgets, the technological advancements in RAM’s performance have also gone up. Over the years, different types of RAMs have been used in phones, each with their unique performance parameters, bottlenecks, and caveats. Even in the latest smartphones, we come across different RAM types.

In this guide, we are going to discuss the different types of RAMs, their differences, and how one is better than the other. This will allow you to study a phone in depth before making a purchase decision.

Brief history of RAM types in phones

Today, mobile phone manufacturers are not using the same RAM variants that were introduced in the 1990s. Instead, technological advancements have enabled them to make cheaper, faster, and less power-consuming RAM modules.

In the 90s, the Extended Data Out (EDO) RAM was common, which maxed out at around 8MBs. Then, in the early 2000s, Synchronous Dynamic (SD) RAM was released. Samsung’s low-power 512MB SDRAM was revolutionary back then and changed the game.

Later, other forms of SDRAM entered the market, such as the Embedded Dynamic RAM (e-DRAM) seen in the original iPhone and other phones. This led to the development of mobile-DDR better known as LPDDR RAM, at the beginning of the 2010s. This was a revolutionary breakthrough, and since then, different iterations of LPDDR RAM have been used across smartphones.

How does RAM work

Each memory type has a specific capacity. It cannot perform functions beyond its capacity, usually given in Gigabytes. In case it has already loaded up applications to its maximum capacity, and the system requires more services from it, the memory will either close the oldest open app or move its data onto the internal storage to make room for running the new app.

The RAM has certain parameters, or specifications, that you should know about. Here are some terms that you ought to be familiar with to fully understand what it means when moving forward while understanding the different RAM types:

  • Memory Clock rate/frequency: It is the frequency of pulses the RAM can achieve in any given second. With each pulse, the RAM performs its task, like reading or writing data to and from the storage. The same pulses are used to synchronize other components of the system. Like all frequencies, the clock rate is also measured in Hertz (Hz). Most clock cycles now are in Mega Hertz or MHz.
  • Data Bus Width/Path: It is the maximum amount of data that can be sent in a clock cycle. It is typically 64 bits in computers and 16 or 32 bits in mobile phones.
  • Bus: The memory bus is the terminal or connector that connects the RAM to the memory controller.
  • I/O (Input/Output) Bus Clock Speed: This is the clock speed of the memory bus, calculated in MHz. It’s the quantity of clock signals transmitted to the memory controller every second.
  • Data transfer rate/bit rate: This is the amount of data sent in a clock cycle. In the case of mobile memory, or LPDDR, this is doubled since it uses both the upstream and downstream of the clock cycle.
  • Memory Bandwidth/Throughput: It is the maximum transfer rate at which data can be written or read from the memory. This is the product of the data transfer rate, number of channels, and the Bus width.
  • Prefetch Size: This represents the quantity of data words read in response to a single data request. It is the quantity of neighboring data words that are read; for example, two adjacent data words will be read if the prefetch size is set to 2.
  • Prefetch Buffer/Cache: Prefetched data is stored in this temporary memory, which runs faster than the main memory and allows the CPU to retrieve it more quickly.

Note: Memory clock rate and the Bus clock speed are two different things. While the different versions of LPDDR RAM have the same memory clock speed, they have different Prefetch sizes, resulting in better performance of the variants with the greater Prefetch sizes.

What is the LPDDR memory?

Low-Power Double Data Rate (LPDDR) is a type of SDRAM targeted toward portable devices, including mobile phones and laptops. As the name suggests, this technology consumes low power, as low as 0.6 volts. Moreover, it is also capable of functioning both when the clock cycle is rising, and when it is dropping.

LPDDR RAM, although used in both smartphones and laptops, is faster for the laptops. This is because, in the laptops, the Data Bus is usually 64 bits. However, in phones, the Data Bus is either 16 bits or 32 bits, except for a few exceptions where the Bus is 64 bits in the flagship models.

Types of LPDDR RAM

In a Double Data Rate (DDR) RAM, the data is transferred on both the rising and falling edge of a clock. This means that when the voltage is applied, the RAM performs its task, and when the voltage is zero again, the RAM performs another step in the task.

ram frequency
Clock rate example of DDR RAM

DDR RAM functions on the falling and rising of the clock, as illustrated in the image above. However, it consumes a lot of power, which is why DDR RAMs are best suited for laptops and desktop computers. However, the innovative low-power DDR RAMs are ideal for mobile phones, as they do what the name implies – consume less power.

Over the years, different variations of LPDDR RAM have made its way to consumer devices.

LPDDR (1)

With a few modifications to make it acceptable for mobile devices, the first version of LPDDR is derived from the adoption of DDR SDRAM. This kind of RAM was seen in some early 2010s devices, including the iPad 1st version, Moto Droid X, and some others.

With the LPDDR1 and LPDDR1e, the speeds are 400 Megatransfers Per Second (MT/s), and 533 MT/s, respectively. The LPDDR1 RAM was a significant advancement in mobile RAM technology. However, it’s quite doubtful that you’ll find a modern smartphone using it today.

LPDDR2

The LPDDR2 offers improvements in performance, form factor, power consumption, and memory capacity. The memory capacity could be increased up to 8GB by using the LPDDR2 interface, which first enabled shared Non-Volatile Memory (NVM) and SDRAM. Moreover, its 1.2V core voltage, as compared to LPDDR1’s 1.8V core voltage, results in 50% more power efficiency than its predecessor.

Moreover, it can handle more data at a time and at a quicker rate, which results in a faster execution time. It also has a data width of x8, x16, and x32 and doubles the data rate of LPDDR1. By utilizing this breakthrough technology, Samsung was able to create a 20nm 4GB LPDDR2 DRAM that could provide up to 2GB of RAM, enabling smartphones to be both more RAM-rich and thinner.

Devices with it included the Blackberry Porsche Design, iPhone 4S, Samsung Galaxy SII Plus, and Nokia Lumia 800.

LPDDR3

LPDDR3 used the same interface as the LPDDR2. Therefore, there was no need for a new design when it superseded LPDDR2 in 2013. With this, the bandwidth could be increased by 50%, from up to 8.5GB/s to 12.8GB/s, and implemented the On-Die Termination (ODT), which makes system operation more efficient.

Furthermore, compared to LPDDR2, which had a maximum memory density of 8GB, LPDDR3 offered a higher memory capacity of up to 32 GB, and improved power efficiency as well. Beyond only supporting 1080p video playing on larger displays, the LPDDR3 pushed the envelope by enabling 1080p content streaming for an improved visual experience.

Additionally, the LPDDR3e offered a higher data rate of up to 1600 MT/s and 2133 MT/s. SoCs that support 800MHz LPDDR3 include the Exynos 5 Dual, Snapdragon 600, and 800. The Samsung Galaxy S4, iPhone 6, and Tecno L3 are a few smartphones with LPDDR3 RAM.

LPDDR4 and LPDDR4X

LPDDR4, developed in 2014, became a necessity when more was demanded from mobile phones. Its performance was significantly enhanced to support features like 4K, slow-motion video, facial recognition, low latency, and reduced boot and loading times. With an even higher data rate of 4266MT/s (lower in the real world) and a bandwidth of 25.6GB/s with a data width of x64, the LPDDR4 excelled in its time of rise.

The LPDDR4 can accomplish all of this while running at a lower voltage of 1.1V, which results in reduced power consumption. To increase operating speed, LPDDR4 features a two-channel die with 16 bits per channel and a shorter data route than LPDDR3’s one-channel die.

LLDDR3 vs LPDDR4
LLDDR3 vs. LPDDR4

The LPDDR4X goes one step further by increasing the data rate to 4266MT/s while lowering the I/O operating voltage from 1.1V to 0.6V.

LPDDR5 and LPDDR5X

In 2019, JEDEC released the LPDDR5 standard, which, like its preceding generations, twice the data rate of the LPDDR4X and increased the data rate of the LPDDR5 standard by 50 percent, with a 6400MT/s data rate. This innovation was needed with the 5G technology on the verge and the CPUs getting better and faster.

Additionally, LPDDR5’s innovative multi-clocking architecture and Dynamic Voltage Scaling (DVS) decrease RAM frequency and voltage, making it more power-efficient. LPDDR5 can handle core voltages of 1.05V and 0.5V when operating at high frequency, and 0.9V and 0.3V when operating at a lower frequency thanks to DVS.

Later, in 2021, LPDDR5X was released which further enhanced the performance. It increased the memory clock rate to 533MHz and the Bus clock rate also went up to 4276MHz.

Types of phone memory – Summary

The table below summarizes the major differences between the different steps of RAM types that are found in smartphones:

SpecificationsLPDDR1LPDDR2LPDDR3LPDDR4LPDDR5LPDDR5X
I/O bus clock frequency (MHz)200, 266.7 (For LPDDR-1E)400, 533.3 (For LPDDR-2E)800, 1067 (For LPDDR-3E)1600, 2133 (For LPDDR-4X)32003750/4266.5
Prefetch size2n4/2n8n16n16n16n
Data transfer rate (Mbps)400, 533.3 (for LPDDR-1E)800, 1067 (for LPDDR-2E)1600, 2133 (for LPDDR-3E)3200, 4267 (for LPDDR-4X)64008533
Supply voltage (Volts)1.81.2, 1.81.2, 1.81.1, 1.8
I/O voltage: 0.6
1.05, 0.9
I/O voltage: 0.5, 0.3
1.05, 0.9
I/O voltage: 0.5, 0.3
Memory Density/Capacity128Mb – 2Gb256Mb – 2Gb1Gb – 8Gb4Gb – 24Gb4Gb – 24Gb8Gb – 24Gb
Memory Clock200
1E: 266.7
200
2E: 266.7
200
3E: 266.7
200
4X: 266.7
400400
Summary of mobile phone RAM types

Takeaway

When purchasing your next mobile phone, make sure to go through this article which explains the different RAM types and their specifications. Make sure you get the best bang for your buck.

The type of RAM will greatly impact the performance of the phone, including its AnTuTu score.

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