Welcome to yet another interesting video from Practical Ninjas.
Everyday we hear that new smartphones getting released.
In this age of competition in the smartphone industry, every brand tries to market their
product with new set of features and technologies.
The main component in any smartphone is the SOC used inside.
SOC stands for System on Chip.
This video will focus on the SOC used inside the smartphones.
Stay tune till the end of the video to understand about the SOC.
All the processing takes place inside this SOC and any feature that the smartphone can
support depends on the SOC.
We hear about various SOC present inside different smartphones like Snapdragon 625, 835 , MediaTek
P-25 etc How do we know which is the best and powerful?
We will try to understand some of the jargons in the processor industry.
The first thing to understand is that the SOC is built on a specific architecture design.
We may have heard about ARM processors.
What is ARM and then what are Snapdragon, Mediatek, Broadcom?
Well, ARM is the company that makes blueprints and architecture of different processors,
for eg.
Cortex-A9, Cortex-A53, Cortex-A72 etc, but never manufactures them.
Other SOC manufacturing companies obtain license from ARM to build these processors and manufacture
SOC.
So, the first thing in an SOC is the architecture or blueprint of the CPU.
SOC can contain multiple CPU units and they need not be the same type.
eg, Snapdragon 650 contains both Cortex-A72 and Cortex-A53.
The next thing to understand about the SOC is the number of cores.
We hear specifications like dual-core, quad-core, octa-core, deca-core.
They refer to the number of available processing units.
Dual stands for 2, quad is 4, octa is 8 and deca means 10 cores.
Depending upon the number of cores, that many simultaneous processes can be performed by
the SOC at a single time.
Having more number of cores, reduces the time taken by a SOC to finish a certain task.
To understand this better, let us look at the water distribution analogy shown in the
figure.
In the figure, we can see two tanks.
One is completely filled with water and the next one is empty.
The task is to transfer water from one tank to another.
Here a single pipe is connected between the two tanks.
It takes some time to transfer the water.
Now instead of a single pipe, let us connect another pipe, making the supply pipe a dual
assembly.
The time taken to transfer water is reduced here.
Similarly, the time taken to accomplish the task of transferring water reduces if quad-assembly,
octa-assembly or deca-assembly is used.
So basically, we can think of these pipes as number of cores in a processor.
More the number of cores, less will be the time required to finish a certain task by
SOC.
However, drawback of this is the power supply requirement.
More CPU cores means more power is required which drains the phone battery faster.
The processors are built using lakhs and lakhs of transistors.
The transistors keep on switching continuously.
Tasks are accomplished when charges flow through these transistors and charges flow when transistor
switches.
The switching speed of these transistors is controlled by an external clock.
The speed is determined by the clock frequency.
We may have heard processors with 1.6GHz frequency, 2 GHz frequency.
2Ghz means the clock will output 2 000 000 000 (2 billion) pulses in one second.
Higher the clock frequency, higher would be the switching speeds in transistors and thus
it would take less time to finish a certain task.
The next important aspect of SOC is on which technology the processor is built.
There are many technologies present like 22nm, 20nm, 16nm, 14nm.
As seen earlier, we know processors are built using transistors, and charges travel through
these transistors.
14nm refers to 14 nanometers ie. 14 * 10 ^-9 meters, This is the generally the width of
the gate in a transistors.
Less the distance, more would be the processor speed and less would be power consumption
as charges have to travel less distances.
Less the distance, the dimension of the SOC is also less.
One might think there is not much difference between 22nm and 14nm, and how can it make
considerable difference in speed and power consumption.
Let us look at it in this way.
Charges are nothing but electrons.
The radius of an electron is less that 10^-18m.
So, for 14nm, a charge has to travel 14 000 000 000 (14 billion) times its radius length.
For 22nm, the distance would have been 22 000 000 000 (22 billion) times its radius.
To get this into perspective, consider electron as a soccer ball or foot ball having radius
of 11cm.
For 14nm analogy, this ball has to travel a distance of approximately 1540000 (1.5 billion)
km or 956,911 (956 thousand) miles and for 22nm analogy, the ball has to travel of approximately
2420000 (2.5 billion) km or 1503718.285 (1.5 million) miles.
From these distances we can understand the vast difference in 22nm and 14nm technology
and how the later is way better than the previous one.
To sum this video up, we discussed how the SOC is built on the architecture blueprints
obtained from ARM, the number of cores that make up a processor, the clock frequency and
how it affects the SOC performance as well as the technology on which the processor dye
is based.
The processors nowadays have become so powerful that they can run a full fledged PC OS on
it.
Before ending this video let us compare Qualcomm Snapdragon 625 and MediaTek Helio P-25 based
on the parameters discussed here.
Both the SOC’s are based on 64bit ARM Cortex A-53 blueprints.
Both are octa-core processors.
Snapdragon 625 is clocked at 2.0 GHz and Helio P-25 at 2.6 GHz.
Snapdragon 625 is based on 14nm technology whereas Helio P-25 is based on 16nm process.