8/3/2019 How Basically Cell Works

http://slidepdf.com/reader/full/how-basically-cell-works 1/5

How basically Cell-phone works?

In this lesson we are going to take a brief familiarization of a typical block diagram of a

cellphone.

Block Diagram can help us understand the flow of a certain part of a cellphone's circuit.

A Cell-phone handset is basically composed of two sections,which is RF and Baseband Sections.RF

RF refers to radio frequency, the mode of communication for wireless technologies of allkinds, including cordless phones, radar, ham radio, GPS, and radio and television

 broadcasts. RF technology is so much a part of our lives we scarcely notice it for its

ubiquity. From baby monitors to cell phones, Bluetooth® to remote control toys, RFwaves are all around us. RF waves are electromagnetic waves which propagate at the

speed of light, or 186,000 miles per second (300,000 km/s). The frequencies of RF

waves, however, are slower than those of visible light, making RF waves invisible to the

human eye.

Baseband

In signal processing, baseband describes signals and systems whose range of frequencies

is measured from zero to a maximum bandwidth or highest signal frequency. It is

sometimes used as a noun for a band of frequencies starting at zero.In telecommunications, it is the frequency range occupied by a message signal prior to

modulation.

It can be considered as a synonym to low-pass.Baseband is also sometimes used as a general term for part of the physical components of 

a wireless communications product. Typically, it includes the control circuitry

(microprocessor), the power supply, and amplifiers.A baseband processor is an IC that is mainly used in a mobile phone to processcommunication functions.

Basically Baseband also composed of to sections which is the Analog and DigitalProcessing Sections. So, we are going to separate each other for better and easier to

understand.

Cell-phone have three different sections which is the following.I prepare this to be simple and easy instead of using or explaining it with deep technical

terms .

In this manner, it is easy for us to understand the concepts and methods of how basically

the cellphone works.

Cell-phone have three sections since baseband is differentiated by into two which is the

Analog and Digital function while the RF section remains as a whole circuit section..which is the following cosists.

1. Radio Frequency (RF Section)

2. The Analog Baseband Processor

3. And the Digital Baseband Processor.

8/3/2019 How Basically Cell Works

http://slidepdf.com/reader/full/how-basically-cell-works 2/5

Radio Frequency Processing SectionThe RF section is the part of the cell-phone circuit is also known as RF Transceiver.

It is the section that transmit and receive certain frequency to a network and synchronize

to other phone.

The RF - A radio section is based on two main Circuits.

1 Transmitter

2 Reciever

A simple mobile phone uses these two circuits to correspond to an other mobile phone. ATransmitter is a circuit or device which is used to transmit radio signals in the air.and a

reciever is simply like radios which are used to recieve transmissions(Radiation) which isspread in the air by any transmitter on a specific frequency.

The two way communication is made possible by setting two transmitters and two

recievers sycronized in this form that a trasmitter in a cell phone is syncronised with thefrequency of other cell phone's recieving frequency same like the transmitter of second

cell phone is syncronised with the recieving frequency of first cell phone. So first cell

 phone transmits its radiation in the air while the other phone listens it and same process is present in the opposit side. so these hand held two cell phones correspond to one another.

the technology used in these days is a little bit different but it is based on the basic theory

 prescribed before. the today's technology will be discussed in later on.

8/3/2019 How Basically Cell Works

http://slidepdf.com/reader/full/how-basically-cell-works 3/5

Analog Baseband ProcessorA/D and D/A section

The analog baseband processing section is composed of different types of circuits.This section converts and process the analog to digital (A/D) signals and digital to

analog signals (D/A).Control section

This is the section acts as the controller of the the input and output of any analog anddigital signal.Power Management

A power management section in mobile phones is designed to handle energy matters that

is consumed in mobile phones. There are two main sub sections in a single power section.

• Power Distribution and switching section• Charging Section

A power distribution section is designed to distribute desired Voltages and currenst to the

other sections of a phone. this section takes power from a battery (which is figured

commonly 3.6 Volts)and in some places it converts or step down to various volts like 2.8V 1.8V 1.6V etc.while on other place it also

steps up the voltage like 4.8 V. this section is commonly designed around a power IC(andintegrated circuit) which is used to distribute and regulate the voltage used in other components.

The Charging section is based on a charging IC which takes power from an external

source and gives it to battery to make it again power up when it is exhausted. this sectionuses convertibly 6.4 V from an external battery charger and regulates it to 5.8V wile

giving it to battery. The battery is made charged by this process and it is ready to use for 

the next session (a battery session is a time which is provided by the manufacturer of a

8/3/2019 How Basically Cell Works

http://slidepdf.com/reader/full/how-basically-cell-works 4/5

cell phone for standby by condition of a mobile phone or talk condition.)Audio Codecs Section

This section where analog and digital audio properties being process like the microphone,earpiece speaker headset and ring-tones and also the vibrator circuits.

Digital Baseband ProcessorThis is the part where All Application being process. Digital Baseband Processor sectionis used in mobile phones to handle data input and ouput signal like switching, driving

applications commands and memory accessing and executing.

These are the parts and sections o a Digital Baseband Circuit were installed.

CPUCPU( Centeral Processing Unit) The Central Processing Unit (CPU) is responsible for 

interpreting and executing most of the commands from the users interface. It is often

called the "brains" of the microprocessor, central processor, "the brains of the computer"Flash and Memory Storage Circuits

*RAM( Random Access Memory)

*ROM,Flash(Read Only MemoryInterfaces such as the following were also part on this section:

*Blutooth

*Wi-fi

*Camera*Screen Display

*Keypads

*USB*SIM-Card

8/3/2019 How Basically Cell Works

http://slidepdf.com/reader/full/how-basically-cell-works 5/5

Here a typical overview of a block diagram on latest mobile phone designs.

Various mobile phones have different concepts and design on every aspects, but the

methods and operational flow are all exactly the same. It differs on how and what certain

IC chips and parts they are being used and installed to a certain mobile phone circuitry.