Types oF diodes in Mobile Phone

A solid state device with two electrodes which passes only the electric current of a particular polarity from one side in called diode. Solid state diode is generally made of germanium or silicon semiconductor. This is used for rectification and switching.

Several types of diodes are used in electronic instruments and gadgets. Chip diodes are used in mobile cell phones and other telecommunication devices. These are surface mount devices (SMD). Surface mount devices are soldered with special soldering technique called SMT.

Important facts about diodes:

1. Indicating Character of Diode : D or V
2. Function: Making AC to DC (Converting) and Do the Switching.

P-N Junction Diode

Diode Symbol

Components made with the combination of P-Type and N-Typesemiconductors are called diode. They are also called P-N Junction Diode.

P-type part of the diode is called anode and N-type is called cathode. The point where both these sides combine is called depletion layer because in this section, the electrons and holes remain neutral and do not attract each other. Due to this depletion layer, the electrons from either side cannot unite.

How Does Diode Work?

The required voltage to activate a diode is called diode biasing. Biasing is of two types –

1. Forward Biasing; and
2. Reverse Biasing

Forward Biasing

When positive supply is given on the anode and negative supply is given to the cathode, it is called forward biasing. This creates HOLE in anode (P-area) of diode and pressure is created on cathode (N-area) because equal charges repel each other. As the pressure continues to increase, resistance of the depletion layer (Junction) decreases to zero and the current flow starts.

Reverse Biasing

Supply of negative to anode (P) terminal and positive to cathode (N) terminal is called reverse biasing. As a result, the HOLES of anode of the diode attract the electrons of battery and the positive terminal of the battery attracts the electrons of the cathode and the resistance of depletion layer goes on increasing and stops the flow of current.

What is Rectification?

Mostly AC is used for electrical energy but in some cases DC has to be used. The process of conversion of AC to DC is called rectification.

What is Signal Diode?

This type of diode is used for detecting signals. These diodes are made of glass. A red ring on the terminal marks its cathode. These diodes are available in following numbers – IN4 148, IN34, OA79 etc. SMD signal diode is also available in black color.

What is Zener Diode?

Zener Diode

This is a special type of diode made with silicon which is used to keep the output supply stable. Zener diodes are used to stabilize voltage. Zener diode is represented by “Z”. Zener diode is recognized by its “Zener Volt” like 3.0VZ, 3.9VZ, 5.1VZ, 6.2VZ etc.

What is Varacter Diode?

This is a variable capacitance diode which functions on the principle of variable capacitor. These diodes function within a defined range of capacity. Varacter diodes are available in the values ranging from 1 to 500 pf and 10 to 100 V. These are used in the signal transmission circuits.

What is Tunnel Diode?

These diodes are used for processing the properties of negative resistance and are used for switching at microwave frequency level.

What is LED or Light Emitting Diode?

LED Diode

These are diodes that produce light after receiving forward biasing. They are used to en light the display or keypad in mobile cell phone.