What is an amplifier?

What is an amplifier?

1. Electronic device that increases the voltage, current or power of a signal.

2. Kind of uses

   • Wireless Communication
   • Acoustic pickups
   • Audio equipment
   • Boardcasting

3. Classification

   • Weak-signal amplifier
     • Wireless recivers
     • Commonly found in FET
   • Power amplifier
     • Transmitters
     • Commonly found in bipolar transistor

4. Characheristic

   • Gain
     • It's the increase in signal power
     • Symbolized with letter 'A', and expressed in decibel
   • Bandwidth
     • Range of frequencies for which the amplifier gives "satisfactory performance"
   • Efficiency
     • Measure of how much of the powersource is usefully applied to the amplifier's output
   • Cascade application
     • Used when a single-stage amplifier is not sufficent for a particular purpose
     • This configuration is created by connecting 2 or more amplifiers one after another
     • The total gain is the product of each gain

5. Inconvenience

   • Noise and distorsion
     • Unwanted signal that degrade the desired signal content in the system
     • It's found in 2 different types, the first it the noise generated by the system itself and the second is the noise recived in the input
     • To avoid these problem a general techinque called negative feedback is used.
       • Portion of the output is fed back and compared with the input signal to stabilise amplification and reduce distortion