Amplifier in Wireless World

Prepared by :Reem R. Hussein

Prof. Issam Rashid Ashqer

An-Najah National university

Faculty of science Physics department

Introduction:

Amplifier How amplifier works?The amplifier gain How to divide amplifiers?Wireless world Wireless networkWhy we use the wireless

technology? Power Amplifiers for Wireless

Systems

Amplifier:We see amplifiers in almost all the electronic equipment around us.

Though we usually relate them to stereo equipment they are also found in TV’s, computers, MP3 players and so on. All these devices have a speaker which is used to reproduce the original sound.

So amplifier is electronic equipment that increases strength of signals passing through it

How amplifiers work?

A sound is said to be amplified, when the device makes the sound louder than usual with the same clarity

•When referring to electronic circuits, the signal used in an amplifier is mostly either current or voltage.

•Therefore an amplifier is a device that is used to change the amplitude of a signal.

•This increase in amplitude can be calculated by a factor known as transfer function, which is actually the ratio between the output and input given to the amplifier. The magnitude of this transfer function is called the gain of the amplifier.

Power gain : = or =10 log() dbVoltage gain : = or =20 log() db

• The amplifiers are divided according to :

1.the source that is supposed to be amplified 2.the driving device3.the frequency of the signal 4. the type of signal.

•Example :The source can be an electric guitar the driving device can be a head-phone amplifier. The frequency of the signal is defined in its range like audio, IF, RF, VHF and so on. The type of signal refers to two parameters inverting and non-inverting.

Wireless World :•Wireless communication is the transfer of information between two or more points that are not connected by an electrical conductor.

•The most common wireless technologies use electromagnetic wireless telecommunication, such as radio.

Wireless networking•a telecommunications network allows computers to exchange data

• is used to meet many needs. Perhaps the most common use is to connect laptop users who travel from location to location. Another common use is for mobile networks that connect via satellite.

•A wireless transmission method is a logical choice to network a LAN segment that must frequently change locations.

The following situations justify the use of wireless technology:

1.To span a distance beyond the capabilities of typical cabling,

2.To provide a backup communications link in case of normal network failure

3.To overcome situations where normal cabling is difficult or financially impractical4.To remotely connect mobile users or networks

Power Amplifiers for Wireless

SystemsThe last output stage in every wireless system includes some form of RF power amplifier (PA) to send the signal to the antenna.

Depending on the frequency band the wireless system uses, the power output, and the efficiency desired

•Systems such as cell phones; Wi-Fi, and WiMAX adapters; wireless routers and access points; Bluetooth and many others all have significant differences in their RF power outputs, frequency bands, efficiency requirements, and cost.

Thus, having a wide variety of PA options allows designers to optimize the wireless system to make the best cost/performance trade-off.

•The more efficient the PA, the longer the talk time or the longer a Wi-Fi connection can be sustained. Line-powered systems such as base stations, routers, and access points usually require higher-power outputs and thus have higher active currents

Problem :

•The power amplifier in any wireless system typically consumes a significant amount of power when transmitting, and often continues consuming significant power as long as it on, even though it may not be transmitting any data.

•The latest generation of PAs are changing that, thanks in part to new standby capabilities that considerably reduce the standby mode power consumption, and increase transmit efficiency when the wireless system is transmitting.

the solution:

•This article examined the latest architecture and process developments in power amplifiers that result in more-efficient and lower power systems, which, in turn, will translate into longer battery life

Thank you

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