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What Does an RF Amplifier Do

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An RF amplifier is a device that amplifies radio frequency (RF) signals. These devices are widely used in wireless communication systems such as cellular phones, Wi-Fi routers, Bluetooth headsets, and satellite receivers. Here are the functions of the RF amplifier.

Amplify Radio Frequency Signals

The main function of an RF amplifier is to increase the power level of RF signals to meet the maximum output power specification of the device. These devices must handle large amounts of energy while maintaining their high fidelity. When you talk on your cellphone for hours, chances are it will drain your battery very quickly.

If you use your phone with its speaker set at full volume, then your battery might last only 20 minutes or so. But if you lower the volume and watch your screen, it can last over 40 minutes. You have heard about ‘power saving’ and ‘screen saver’ features. They work because the audio amplifier does not consume much power when no input signal is present to amplify.

Protect Against Overload

It protects the circuit from damage due to excessive RF voltage between the supply voltage rails. In many cases, it acts as a filter by absorbing some of the incoming signals before reaching critical components like transistors and other circuitry parts. However, if it fails to protect the circuit adequately, the device could get damaged. For example, the transistor in the mobile telephone transmitter might fail because of the excessive RF voltage failing the entire device.

Increase Signal Strength

With too little amplification, the original signal gets lost in noise which prevents you from hearing the signal properly. With too much amplification, you get distortion which distorts the signal badly. So, an RF amplifier needs to provide just enough gain without causing any distortion.

You can do this by controlling the gain available for each stage using attenuators. One way of doing this is to apply a variable resistor across the inputs and outputs of the amplifier. Another way of doing this is by using an electronic switch that reduces the RF voltage gradually until it goes away completely.

Minimize Distortion

An ideal amplifier generates pure sine waves and amplifies them perfectly without generating unwanted harmonics. But real-world amplifiers often generate distorted sine waves. Since these harmonics distort the original signal, it is important to minimize them. Using a combination of filters and variable capacitors allows the circuit designer to reduce these effects.

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In conclusion, an RF amplifier provides various functions to listen to music, receive radio broadcasts, watch television, and communicate via cellular phones. Most modern amplifiers offer additional adjustable levels, variable gains, and automatic volume control.


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