Mobile hardware– other components

Mobile phone and tablet batteries have come a long way since it’s inception. From being the bulk of the mass of an ordinary phone back in the 90’s to being one of the lightest components these days. However, phones have gotten a tad light too and even now the battery can be said to be roughly half the phone’s weight.


When it comes to performance parameters, we always seem to care most about the CPU and GPU. The other components play an equal role too.


Mobile phone and tablet batteries have come a long way since it’s inception. From being the bulk of the mass of an ordinary phone back in the 90’s to being one of the lightest components these days. However, phones have gotten a tad light too and even now the battery can be said to be roughly half the phone’s weight. 

Battery technology has also come a long way, in the early days a phone needed to be recharged every 12-16 hours and now we hear of a battery that can last a month. This is a bit ambiguous as usage plays a huge factor in the life of a battery. With the advent of smartphones running heavy duty processors the current consumption has gone up again to the point that you need to charge your phone once a day, again.

Battery types

There are several types of batteries in use today like NiMH (Nickel Metal-hydride), NiCd (Nickel Cadmium) but the most popular would be the Li-ion (Lithium Ion) battery. It pretty much comes down to the manufacturer as NiMH and NiCd are cheap but they require frequent recharging and don’t hold as much charge as LiPo(Lithium Polymer) or Li-ion These have been proven to hold enormous amount of electric charge while reducing recharge time. In the last two years itself, companies have come up with more different types of batteries than in the past decade. However, it will be some time before we get to see these enter mainstream usage. Batteries are manufactured according to their usage conditions and hence what may be really efficient in the automotive sector would not perform at par in another form factor. 

Battery rating

When you flip your mobile battery, you’re bound to see a few figures here and there. These figures include certification emblems, safety standards applicable and most importantly the battery type, voltage rating and the battery capacity. A battery is called so as it contains multiple cells, each of which is capable of carrying a certain charge of its own. However, this is very little for general use and thus multiple cells are combined in series/parallel to increase the voltage as well as current capacity.

The voltage rating simply gives the potential difference between the two terminals of the battery. This is pretty much fixed depending upon the type of chemicals used in the construction of the battery. For Li-ion batteries it can be 3.6v, 3.7v or 3.2v.

Charge rating is shown using the unit mAh (milliAmpere-hour). One ampere-hour is equal to 3600 coulombs. Batteries are rated by these two parameters, i.e. voltage and current capacity (mAh). 
The battery life or capacity can be calculated from the input current rating of the battery and the load current of the circuit. Battery life will be high when the load current is less and vice versa. The calculation to find out the capacity of battery can be mathematically derived from the below formulaBattery Life (hours) = (Battery capacity in milliAmpere-hour)/(Load current in milliAmpere-hour) the battery capacity will be mentioned on the battery jacket but the load current being a variable is difficult to figure out. Since it depends on a multitude of factors like the types of components powered on at the moment, each of which consumes a bit of charge. The battery life mentioned on the product packaging cannot really be used to compare one phone to another properly, sure it can give an approximation but since different manufacturers use different methodologies to test the battery life, there exists no standard. Some might test conservatively by just inserting one SIM and not using the phone at all. Others might switch on GPRS, WiFi and Bluetooth and test. Obviously, the latter will show less battery life but on a standard testing scale this may not be the case at all. 

Battery care

Good care must be taken to ensure that a battery lasts a long life, this includes paying attention to it’s charging cycles, the temperature, using the proper charger etc. Here are a few pointers you need to keep in mind.

Your Li-ion battery has a limited number of charge cycles, as time progresses the capacity of the battery is going to reduce by a little bit till the point that you cannot afford to unplug the charger from your phone at all. Also, you really shouldn’t be using a phone while it is charging, they tend to get pretty hot and you risk being one of those lucky few whose phone blows up during use. An average Li-ion battery lasts about 1200 charge cycles. Given there are 365 days in a year and let’s say you charge 300 times a year, your battery should last 4 years before needing a replacement provided you take care of your battery.

Li-ion batteries also suffer from what is termed the memory effect. When a battery is charged after having only been partially discharged, it sort of “remembers” the partial capacity, so the battery will show that it is fully charged when it actually is not. Given the cut-off mechanisms in phones these days, when a battery tells that it is full the phone stops the charging, thus as your progress through charging cycles your battery life reduces by a small amount each time. This is why you should always discharge your phone as much as possible before commencing another charge cycle(i.e plugging the charger in). It was claimed that Li-ion batteries do not suffer from the memory effect, however, recent studies have shown that they do suffer from the memory effect but not the extent that NiMH and NiCd batteries do.

Use as few of your phone’s features as necessary to reduce consumption. Switch off Bluetooth, WiFi, and 3G when not needed. Smart phones these days come with a quick menu wherein these features can be managed without much fuss. Adjust the screen brightness to a level that is easy on the eyes and at the same time lower that half the screen’s brightness to ensure a long discharge cycle.

An important factor for phones slightly older would be to use the proper charger that came with it, as the amperage of the current inflow may cause the battery to bloat if it is higher than what the battery was designed to handle. Nowadays phones  use USB to charge so any compatible outlet should do fine but stay away from cheap chargers as they might not be up to standard and could cause some damage to your device.

Here is a good article on taking care of your battery - http://www.wikihow.com/Make-Your-Cell-Phone-Battery-Last-Longer

Display technology

Display technology has come a long way since the day of miniature screen whose sole purpose was to display the phone number and the name of the caller. Displays these days are pretty much miniature television screens capable of playing full HD 1080p signal. There isn’t much to differentiate between the technology that lies in your TV from that in your phone. Some screens are difficult to manufacture on a scale fit for television, that’s all.

Let’s have a look at the common tech behind your phone displays and a little insight into which is better in terms of viewing experience and energy efficiency.


The predecessor to all displays in the market, TFT-LCD (often termed simply as LCD) are by far the most used display tech, simply because there are a lot of manufacturers offering these and it thus has a good competitive economy about it. If your phone is a mid-range model then most probably it has this type of display but even the high-end Nexus 7 has this display.

TFT stands for thin-film transistor liquid crystal display and there are many different ways of manufacturing these screens, so just by calling it a TFT wouldn’t be of much help to you. Just like in desktop display where VA, TN and IPS, even mobile devices have a lot of different technologies. Thus, they show the same characteristics as desktop displays, i.e. varied colour reproduction, washed out colours at extreme viewing angles etc.

The drawback about TFT displays are that they are pretty thick and are the major contributing factor to the device’s thickness, the other being the battery of course. High quality LCD screens will have bright, accurate colours and with visibility from just about any angle.


AMOLED (Active-matrix organic light-emitting diode) is a screen technology based on organic compounds that offers remarkably better image quality along with potentially very low power usage.
Till OLED screens came into the picture, all display technologies needed a backlight. This was the reason for their thickness, and each pixel would only control the colour shade. This also meant that the backlight would remain on and this 100% of the screen would be on. Unlike LCD screens, AMOLED displays don't need a backlight - each pixel produces its own light - so phones using them can potentially be thinner. Also, since each pixel can be turned off on its own this mean that certain portions of the screen which would be displaying black colour could be turned off completely, this is what most people term as true black, i.e. absence of any light.

It also means that a mostly black screen will use very little electricity, and watching videos the colour reproduction was much better as opposed to TFT where dark regions would be reproduced as dark grey rather than true black.

This being said, AMOLED screens are rather expensive to produce in terms of cost and time, hence, you’ll find these screens only in the upper mid-range and top-end products. Another drawback is that on a sub-pixel level, the arrangement of the subpixel is rather different as compared to LCD, thus there will be a slight distortion when compared to an LCD. High-end LCD screens which are found on certain top-end phones are capable of outdoing the colour reproduction capability of AMOLED screens.


An improvement over traditional AMOLED screens, Super AMOLED screen has superior brightness and colour reproduction. What is primarily different is that these screens have the capacitive touchscreen included in the manufacturing process and do not use a digitizer overlay as is the case in other screens.

Super AMOLED Plus

The subpixel arrangement of AMOLED screens led to a slightly distorted image being produced, with the advent of Super AMOLED Plus, this was fixed as the subpixel arrangement was modified to resemble that of an LCD, thus ensuring a cleaner image.


A step ahead and then a step back, Super AMOLED HD screens had higher resolution but it ended up going back to the subpixel arrangement of normal AMOLED screens. So essentially, the distortion in the image would be so negligible that most casual users wouldn’t notice it. So the expensive process of subpixel arrangement correction was ditched to make cheap, high-resolution images. 

Retina display

When observed closely any display will show the individual pixels on it, but as you move away from the screen this individuality is less visible and you observe a cleaner image. So basically when you increase the pixel density (number of pixels per unit area) the distance at which pixelation is not apparent becomes lesser. So you can hold the screen closer to you is still see a clean image. This is what Apple did, there was no new technology behind the retina display, at the end of the day it all came down to marketing mumbo jumbo. Most screens these days have similar or greater pixel density, so pretty much every display is a “retina” display.


Super-LCD or SLCD is a TFT screen but with characteristics similar to an AMOLED screen, so there is better black colour reproduction which is comparable to that of AMOLED screens. It still has a backlight but is considerably power efficient as compared to the regular TFT screen.

Touchscreen - Capacitive or Resistive

Touchscreens are a vital component of smartphones these days, almost all major platforms have migrated to using touchscreens instead of keypads mostly because of the versatility that a touchscreen offers. Touchscreens are what recognizes where on the screen you’ve placed your finger or stylus and communicates the co-ordinates to the phone CPU accordingly.

There are two popular types of touchscreens available on devices these days, one is the resistive touchscreen and the other is the capacitive touchscreen. The resistive touchscreen has two layers (separated by a miniscule gap) which form an overlay over the screen. When a finger is placed on any point on the screen, the two form a contact and the co-ordinates are obtained. These are relatively cheap to make and are rightly found on most budget phones. The downside is that a certain amount of pressure is required to register a touch so as time goes by some degree of damage does occur to the screen.

The other type is the capacitive touchscreen which has the entire screen coated with a capacitive substance which holds a certain amount of electrical charge, when a conducting object like a finger is placed on the screen, there is a change in capacitance on that point and thus the coordinates are obtained. Capacitive touchscreens don’t respond well in cold climates where the human finger doesn’t cause a change in capacitance, thus a stylus is recommended for such scenarios.

Then there are multi-touch touchscreens wherein almost all fingers can be pinpointed accurately. This has led to an increase in the number of gestures that one can perform on a touchscreen.


Bluetooth is a protocol that allows data transfer between two devices over short distances. It’s ever increasing popularity has led to a plethora of Bluetooth supported accessories for mobile devices with hands-free headsets being the most popular.

Manufacturers have come up with remarkable applications for this technology, however, most of them are being replicated using Wi-Fi. Wi-Fi though slightly more power consuming offers greater range and bandwidth, thus allowing faster and low latency access times. But this did not spell the end of Bluetooth as battery woes will never leave the smartphone and tablets alone in the near future, so a low power option like Bluetooth is a necessity. With Bluetooth 4.0 now appearing in most new devices, it now offers the similar range and bandwidth as that of Wi-Fi but with a lot less power consumption.

Since bluetooth is backwards compatible your old accessories can be used with new devices without much issues, these being that you‘d not be able to reap the benefits of the new features that each revision brings with it. Here is a simple table highlighting the differences between different bluetooth


Wi-Fi or IEEE 802.11 is an older protocol for data transfer but consumed much more power and offered higher range and bandwidth. Wi-Fi too has undergone multiple revisions with multiple improvements in each revision that led to a much efficient system for data transfer. 

Wi-Fi can connect to a host of devices to interconnect and access the internet. This method of connection can require a mediator as in most centralised/decentralised/hybrid systems, however, there also exist methods to enable ad-hoc networks (simple closed group, even one-to-one) like Wi-Fi Direct.

The current revision of Wi-Fi is 802.11ac, however, the average user won’t be able to saturate anything above 802.11n. The current internet services simply don’t offer services that’d need more bandwidth than 802.11n. Then again since it uses a different frequency band there is less interference compared to existing radio technologies. It is the most common and widely used protocol, so anything above that is a luxury. The good thing about this is that it is comparatively power efficient and thus better suited for mobile application and each successive revision will be better. 
Here is a simple table to compare existing Wi-Fi protocols:


Quite simply put memory is of two types, RAM (Random Access Memory) and ROM (Read Only Memory). Both of these are essential in the running of a computer, be it a mobile device or a full fledged desktop. 

ROM is the permanent memory on phones it not only consists on memory chips/modules on the device as well as the extensible memory which is fulfilled by means of a memory card. Whereas RAM is purely on board and is a volatile memory, volatile means that the memory does not retain data upon losing power. They are quite different from each other when it comes to the application of memory. ROM is where data like the applications, images, videos and pretty much everything is stored. The RAM is where data is stored temporarily which needs to be accessed more frequently. So if an application accesses a certain data file way too many times then it might be cached in the RAM to allow faster access, however, this isn’t the primary purpose for which RAM exists. Memory is organised in a hierarchy of memory where the fastest is at the top and the slowest at the bottom. The real fast memory are called registers and exist on the processors themselves and hold elements of mathematical equations and such low level data which is needed immediately. Them comes shared memory which allows multiple processors to share memory, after that comes RAM and then ROM.

However, RAM is not cheap compared to other modes of storage and it is volatile which is why not all forms of memory are made using RAM chips. However, Solid State Drives in computers are coming up with chips very similar to RAM but with less volatility which allows for really fast data transfer. 

How much RAM do you need?

Most applications these days are fine with mobile devices that have 1 Gigabyte of RAM. However, if the past trends are to be studied, more and more applications will soon follow which will need much more ram. It really comes down to the programmer, if the application uses a lot of elements which constantly change then that much more RAM is needed otherwise the programmer can make do with ROM. The downside of this approach is that the application becomes slow to the point that casual users can feel the sluggishness of whatever application is under use currently. This does not imply that any sluggish interface is purely due to lack of RAM, there are a lot more factors that come into play here.

On devices that allow multitasking, even more RAM is needed as each active task will take up a certain amount of memory and cumulatively this would exceed what is available at hand. Worry not! For in such cases there are memory management functions part of the phones operating system which constantly dumps or rather deletes what all is currently not needed. So a background application may have its contents dropped from the RAM so make way for the active application. On devices which don’t allow multitasking, the RAM needed is much less since there would only be one application running at any given time. While most of you might think that the word application refers to just any app that you’d download from the app store or Google play, this actually refers to any subcomponent of the operating system as well. For example, if you have 5 widgets enabled on your home screen, each of that will consume a certain amount of RAM always. Switching of the WiFi or Bluetooth will take up a portion of the RAM. Everything needs RAM to run, which is why it is a very precious resource. 

If you find that after some time that you phone has turned to be a bit sluggish then mostly it has ample amount of background process which are eating up the RAM. Removing these or disabling them show alleviate your RAM woes. So in a nutshell, the more applications you are going to be using, the more RAM you’ll need. Anything around 1 Gigabyte is plenty for the average user.

Extra memory?

By extra memory we do not mean RAM, it’s the extensible memory we are now talking about. The majority of devices in the market come with around 8-16 gigabytes of ROM. While this is enough for some users to host around 60 applications and a few hundred songs and images, the need for more has always existed. Which is why SD cards exist, they might have been limited to the domain of digital cameras in the past but now the usage in smartphones and tablets outnumbers that of cameras by a huge extent. 

SD cards are very popular but are slightly bulky in an age where everything is progressing to a smaller form factor. This led to the introduction of microSD cards which are less than a quarter the size and much thinner. Capacities range from 1GB to 64GB currently, though a 16GB card is more favourable in most aspects including price and storage space. However, if you are intent on carrying your entire music library with you all the time then invest in more memory accordingly. Though, it’d be prudent to remember that almost all devices only come with one slot for extensible memory. Also the letters SD may be succeeded by either HC(High Capacity) or XC(Extended Capacity), this relates to the capacity of the memory and nothing else. Cards between 4-32GB are labelled SDHC and those above 32GB are labelled SDXC, this has nothing to do with quality or speed. Before purchasing a memory card do find out what is the maximum that your smartphone or tablet can support, buying more than the supported amount would not necessarily work or even if it does then expect glitches.

Memory cards are graded according to their data transfer speed or class as it is called in this case. The lower class memory cards are cheaper but not by a huge margin. The following table shows the different memory classes and their respective speeds.

Near field communication

NFC is a relatively new technology that allows communication over very small distances. Currently only found on high-end phones NFC is slowly gaining popularity. More and more applications are discovered with each passing moment. 

NFC is very similar to the way that RFID works, communication can be accomplished between two actively powered devices or between one active and one passive device. The first scenario is where we have two NFC devices brought close together while the latter deals with a NFC tag being swiped over a NFC device or vice versa. The technology consumes next to zero power since the transmission distance very short(often a few centimeters) for active to active communication but when a passive element is to be read, then it has to be “illuminated”(powered wirelessly) which does consume a bit of power. This brings the NFC pretty close to Bluetooth 4.0 VL in terms of energy efficiency.

There is no pairing code in this scenario as is present in Bluetooth, so security concerns regarding what data should be present on an NFC chip have been raised. Across the world there are pilot programmes being conducted to test the feasibility of this new technology. As for India, there hasn’t been anything so far, basically due to poor penetration of the technology, so NFC is mostly used here for contact swapping.

The applications are pretty diverse, we now have mobile phones acting as wallets which can be used at shopping malls, to pay public transport ticket fares, utilise parking meters etc. Then we have interactive advertising posters which can import your details to present you with customised offers and so on. The primary application scenario is to eliminate plastic credit/debit cards which as we all know is pretty sensitive to magnets and scratches on the magnetic strip can wreck havoc.


GPS is one of the many global navigation systems based on satellites in space. It is used to pinpoint your current position accurately within a few meters. There are applications to help you navigate from one place to another, and then there are applications which track your locations and the places you visit to generate social profiles etc. 

GPS requires that your device to establish communication with at least 3 satellites for a geographical location and a further 4th for altitude and error correction. It’s quite a handy feature for tourists to navigate foreign countries and locations outside terrestrial transmission equipment’s coverage.

SIM sizes

With the ever increasing drive to shrink things even the SIM card had to undergo shrinkage. We now have three variants -
•    Mini-SIM
•    Micro-SIM
•    Nano-SIM

This does not mean that you’d have to get a new SIM when you buy your next mobile or tablet. There are special mechanical punch machines which can convert your Mini-SIM to a Micro-SIM. However, punching the same to get a Nano-SIM is not advised as the shearing can cause damage to the SIM card. Also, the thickness of a Nano-SIM is 15% lesser compared to its predecessors so it’s best to contact your service provider and get a new SIM. There are adaptors available to use your Micro-SIM in a Mini-SIM phone, or you could save the punched plastic as an adaptor as well.


Radio is something that has survived quite a lot and still exists in most mobile phones and tablets. Since the technology has remained unchanged for decades there isn’t much new however, phones do come with RDS these days. RDS stands for Radio Data System, it is a protocol by means of which the radio station can embed bits of information along with the regular transmission. 

There are predefined fields which can be transmitted, each field pertains to a certain context. All of this is text based communication. Common fields include :
AF (alternative frequencies) -

If the current FM signal becomes too weak then the receiver can obtain an alternate channel by reading this field and switch to that to get better reception.
CT (clock time)
This field gives the current time as transmitted by the radio station.
EON (enhanced other networks)
This allows the receiver to check other stations mainly for traffic updates.
PI (programme identification)
This field identifies a particular station with the country of origin.
PS (programme service)
On most occasions the only way to Identify a Radio station is by identifying the radio jockey or waits for the station’s unique chime. With the PS field the station can transmit 8 characters to identify itself.
PTY (programme type)
There are 31 predefined program types, using this field the station can identify the current program type. Also, certain radios are programmed to listen for PTY31 which is the emergency broadcast program type.

A radio station without any RDS information.

A radio station which is using the PS and RT fields.

REG (regional)

This field identifies the region of the transmission. In places where transmissions in multiple languages occur or if it is a region close to a national/state border, this can be used to lock onto a certain set of transmissions. Thus it helps in weeding out unwanted transmission stations.

RT (radio text)

This 64 character field can be used to send anything pertaining to the current radio station which the user is listening to. It can be the song title, author or even emergency numbers in case of natural disasters.


There are a multitude of sensors in smart phones these days which has made the device even more versatile. There are light sensors, barometers, and hygrometers, compass to name a few. Let’s have a detailed look at this.


An ambient light sensor makes use of two different types of photodiodes (or light sensors) to each record the level of light currently falling on the screen. By combining the output of these two sensors portable devices such as tablets, smart phones, and laptops can sense a side pectrum of light. Thus it can accurately measure the brightness of the room. This information is then used to adjust the screen brightness to make it easier on the user’s eyes and also helps to extend battery life.

Proximity Sensor

A proximity sensor detects how close a smartphone is to your body thus letting the smartphone know whether you have the screen close to your cheek. In order to save battery life and also to prevent accidental touchscreen input the phone automatically switches these things off. Thus the user can take a call by just placing the phone on their cheek, there is no need to do anything else. All current tasks will be saved and the display switched off for the duration of the call. 


An accelerometer is what reads the acceleration of the device along three axes - X, Y and Z. So when you tilt your phone or flick your phone to change a radio station or skip a song, it is the accelerometer which senses this and performs the appropriate action. These are very sensitive devices which can measure acceleration up to 1G on a fine scale. 


The compass is simply used to figure out the magnetic north and relay the information. However, most electronic circuits these days do not use magnets but instead they rely on the change in a magnetic field around a flow of current to figure out the direction. This is why your compass application demands a calibration each time it is activated. Without the compass sensor your phone will not be able to provide you with directions even if you have the application installed.


A gyroscope is a sensor which can sense the current orientation of the device. So when you slowly tilt your phone or tablet, it is the gyroscope which tells how the device is oriented. Basically when you switch on screen rotation, it is the gyroscope which helps the screen rotate and orient itself in the proper manner. Also, racing games which allow you to use the device as a steering wheel uses the gyroscope to guide the car.

So what’s next?

Recently devices have started featuring thermometers (temperature), barometers (pressure) and hygrometers(humidity). This can be utilised in some creative ways, devices can be powered off if it gets too hot or too wet for proper functioning. Imagine your device with very sensitive information caught up in a fire, it could detect the impending doom and transmit all data to a backup server before going up in smoke!