What is an Amplifier?
An amplifier is an electronic circuit designed to boost the strength of a signal, whether it’s in terms of voltage, current, power, or other characteristics. Its primary function is to take a weak signal at the input and produce a stronger, identical signal at the output. This process of increasing the signal’s strength is referred to as amplification. The extent to which the amplifier increases the signal is measured by a parameter called the gain of the amplifier. In essence, an amplifier enhances the input signal without changing its essential characteristics, making it a fundamental component in various electronic systems and devices.
Difference between Voltage Amplifier and Power Amplifier
| Basis of Difference | Voltage Amplifier | Power Amplifier |
|---|---|---|
| Definition | An amplifier designed to increase the level of input signal. | A type of amplifier designed to boost the power level of the input signal. |
| Alternate Name | Small signal amplifier | Large signal amplifier |
| Voltage of Input Signal | Very low (few mV) | Relatively high (few volts) |
| Nature of Output Signal | High voltage, low power output | High power, low voltage output |
| Size of Transistor Used | Smaller | Relatively larger physical size |
| β Value of Transistor | Relatively high (around >100) | Low (around 5 to 20) |
| Type of Coupling | R-C coupling | Transformer coupling |
| Collector Current (IC) | Low (approximately 1 mA) | Relatively high (greater than 100 mA) |
| Base Region of Transistor | Thin base region (handles low current) | Comparatively thicker (required to handle large current) |
| Load Resistance (RC) | High resistance (around 4 kΩ to 10 kΩ) | Low resistance (around 5 Ω to 20 Ω) |
| AC Power Output | Low | Comparatively high |
| Output Impedance | High (around 12 kΩ) | Low (around 200 Ω) |
| Need of Heat Sink | No need of heat sink | Heat sink is necessarily required |
| Use | Usually used at the first stage of amplification | Usually used at the last stage of amplification |