How do you calculate the voltage gain of a common-emitter amplifier?
1 Answer
To calculate the voltage gain of a common-emitter amplifier, you need to consider the input and output voltages of the amplifier. The common-emitter amplifier is a type of bipolar junction transistor (BJT) amplifier with the transistor configured in a specific way. It is widely used for its moderate input and output impedances and its ability to provide both voltage and current gain.
The voltage gain (Av) of a common-emitter amplifier can be calculated using the following formula:
Av = ΔVout / ΔVin
Where:
ΔVout is the change in output voltage (AC voltage swing).
ΔVin is the change in input voltage (AC voltage swing).
To calculate the voltage gain, you'll need to know the following parameters of the amplifier circuit:
Collector resistor (RC): This is the resistor connected to the collector terminal of the transistor.
Emitter resistor (RE): This is the resistor connected to the emitter terminal of the transistor.
Base resistor (RB): This is the resistor connected to the base terminal of the transistor.
Transistor current gain (β or hfe): This is a characteristic parameter of the transistor, which is usually provided in the datasheet.
Now, let's assume you have an input signal applied to the base of the transistor, causing a change in the input voltage (ΔVin). Due to the transistor's amplification, there will be a corresponding change in the output voltage (ΔVout).
The voltage gain (Av) in a common-emitter amplifier is approximately given by:
Av ≈ -β * (RC / RE)
Note that the voltage gain in a common-emitter amplifier is negative. This means that the output voltage is phase-inverted relative to the input voltage.
Keep in mind that this is a simplified formula, and there are other factors that can affect the actual voltage gain of the amplifier, such as parasitic capacitances and variations in the transistor's characteristics.
Remember that in practice, transistor amplifiers are designed and analyzed using small-signal models to account for nonlinearity and to obtain more accurate results. The above formula, however, provides a basic understanding of voltage gain in a common-emitter amplifier.
The voltage gain (Av) of a common-emitter amplifier can be calculated using the following formula:
Av = ΔVout / ΔVin
Where:
ΔVout is the change in output voltage (AC voltage swing).
ΔVin is the change in input voltage (AC voltage swing).
To calculate the voltage gain, you'll need to know the following parameters of the amplifier circuit:
Collector resistor (RC): This is the resistor connected to the collector terminal of the transistor.
Emitter resistor (RE): This is the resistor connected to the emitter terminal of the transistor.
Base resistor (RB): This is the resistor connected to the base terminal of the transistor.
Transistor current gain (β or hfe): This is a characteristic parameter of the transistor, which is usually provided in the datasheet.
Now, let's assume you have an input signal applied to the base of the transistor, causing a change in the input voltage (ΔVin). Due to the transistor's amplification, there will be a corresponding change in the output voltage (ΔVout).
The voltage gain (Av) in a common-emitter amplifier is approximately given by:
Av ≈ -β * (RC / RE)
Note that the voltage gain in a common-emitter amplifier is negative. This means that the output voltage is phase-inverted relative to the input voltage.
Keep in mind that this is a simplified formula, and there are other factors that can affect the actual voltage gain of the amplifier, such as parasitic capacitances and variations in the transistor's characteristics.
Remember that in practice, transistor amplifiers are designed and analyzed using small-signal models to account for nonlinearity and to obtain more accurate results. The above formula, however, provides a basic understanding of voltage gain in a common-emitter amplifier.