GSM Integrated Circuit – JSS3 Computer Hardware & GSM Repair Lesson Note (First Term)

Class: JSS 3

Subject: Computer Hardware and GSM Repair

Topic: GSM Integrated Circuit

What is an integrated circuit (IC)?

An integrated circuit (IC) is a tiny electronic chip that holds many small electronic parts on one piece of silicon.

• Where to see it: open a broken radio or mobile phone and look at the green board.
• What it looks like: small, black, square objects with metal “legs” or tiny silver balls underneath.
• Short name: an integrated circuit is also called an IC or a chip.

Behavioural objectives

By the end of the lesson, students should be able to:

1. Define an integrated circuit and state why ICs are used in phones.
2. Name and state the job of the main ICs in a mobile phone.
3. Link common phone faults to the IC that may cause them.
4. Define a microprocessor and state its functions and key parts.
5. Explain the difference between a general IC and a microprocessor.

Why are ICs important in a GSM phone?

ICs make a phone small, fast and able to save battery power.

The “city in a box” idea

• The picture: imagine a whole city with houses, wires and streetlights shrunk onto a piece of silicon the size of your fingernail.
• The problem before ICs: parts such as transistors and resistors were big and joined with many wires.
• The solution: many tiny parts are built onto one single chip.

Benefits of ICs in a phone

• Small size: the phone is easy to carry in a pocket.
• Low power use: the battery lasts longer.
• High speed: parts sit close together, so the phone works fast.
• Fewer wires: there are fewer loose connections to fail.

What are the types of ICs in a mobile phone?

A mobile phone has many ICs, and each one has a special job, like the organs in your body.

The main ICs taught at this level are the power IC, the network (RF) IC, the audio IC and the charging IC.

1. The Power IC

• Job: it is the “heart” of the phone. It takes power from the battery and sends the right amount to every other part.
• Fault sign: the phone will not switch on at all. It is “dead”.

2. The Network IC (RF IC)

• Job: it is the “ear and mouth” of the phone. It handles radio signals from network masts such as MTN and Airtel.
• Use: it helps you make calls and browse the internet.
• Fault sign: the screen shows “No Service” or “Searching for Network”.

3. The Audio IC

• Job: it controls sound. It manages the microphone so people can hear you.
• Speaker: it also manages the speaker so you can hear them.
• Fault sign: little or no sound, or the caller cannot hear you.

4. The Charging IC

• Job: it manages the energy coming from the charger.
• Protection: it helps protect the battery from overcharging and stops charging when the battery is full.
• Fault sign: the phone does not charge, or charges wrongly.

Summary of faults and ICs

What is a microprocessor?

A microprocessor is a very advanced IC that follows instructions and controls the other parts of the phone.

• Simple picture: it is the “Governor” or “Headmaster” of the phone.
• In use: when you tap an app, send a text or take a photo, the microprocessor does the “thinking”.
• Orders: it gives instructions to the other parts.

What are the functions of the microprocessor?

1. Processing data: it does the maths and logic needed to run games and apps.
2. Control: it tells the screen what to show and the speaker what to play.
3. Storage access: it goes into the memory to fetch saved photos and videos.

What are the key parts of a microprocessor?

• ALU (Arithmetic Logic Unit): does the “sums” and comparisons.
• Control Unit: acts like a traffic warden, directing data where to go.
• Registers: tiny, very fast storage areas used while the processor is working.

What is the difference between an IC and a microprocessor?

Every microprocessor is an IC, but not every IC is a microprocessor.

• IC: the name for the chip “package”. Many ICs are specialists that do one job, such as handling only sound or only power.
• Microprocessor: a special, smart IC that can be programmed to do many different things.

Evaluation

1. Explain what an Integrated Circuit (IC) is in your own words.
2. Which IC is responsible for the phone showing “No Network”?
3. Why is the microprocessor called the “brain” of the phone?
4. If a phone is “dead” and will not charge, which two ICs might be faulty?
5. Name the three key parts of a microprocessor and state one job of each.

Assignment

Draw a table with three columns: IC name, job, and fault sign. Fill it in for the power, network, audio and charging ICs.