What is a Bipolar Amplifier?

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  • Written By: Alexis W.
  • Edited By: Heather Bailey
  • Last Modified Date: 12 January 2017
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A bipolar amplifier is a signal amplifier that has the ability to emit more than one output signal. The output is determined by either the positive or negative polarity of the signal upon input to the amplifier circuit. The bipolar amplifier is not only able to emit multiple signals that correspond to the input polarity, but it is also able to add gain to the signal as the input signal is passed through it. This allows for an input signal that results in low noise incurrence, which is a common problem among different amplifier circuits.

The circuit layout of a bipolar amplifier is designed to minimize the amount of noise within the amplifier circuit itself. In fact, any amplifier used, whether bipolar in nature or not, must be designed in a manner that produces as little noise as possible. If the circuit is not designed to minimize noise, the noise created will accompany the output signal in the form of an amplified signal.

The design of a bipolar amplifier is a simple one. The input signal is matched in noise impedance upon the receiving of the signal. Noise generated throughout a circuit is usually caused by the components located in the front end of the circuit itself, and the design of the bipolar amplifier minimizes this.


Bipolar amplifiers have an advantage over other amplifier circuits in the noise reduction aspect of the circuit due to the way the amplifier’s circuit itself is laid out. Most of the noise that occurs within a circuit is caused by the continuous transfer of the input signal from circuit component to circuit component. The fact that the layout of a bipolar amplifier is not conducive to the production of electronic noise and that the amplifier is usually located in the front end of the device circuit is a significant advantage to the amplifier.

Another advantage to using the bipolar amplifier at the beginning of a device circuit is that any noise in the input signal to the amplifier is reduced through the natural noise-reducing tendencies of the amplifier. This is true regardless of the polarity of the input signal. As a result, bipolar amplifiers are often used in both AM and FM radio transmissions as a means of adding gain to the input signal’s power without adding gain to any noise in the signal itself.


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