The voltage gain of a common emitter transitor amplifier is (inverted) collector resistor divided by emitter resistor, unless this would exceed hfe or the transistor is operating in non-linear mode.
A bipolar transistor can be used in different configurations in linear electronic design. Most well known is the common emitter CE configuration with a base current as input signal resulting in a collector signal multiplied by the current gain factor. The second configuration is known as the emitter follower or common collector configuration. Here the input signal is in the form of a voltage between the base and the common connection. The output signal is found in the form of a voltage at the emitter with a relative low output impedance. The voltage swing at the input is almost as large at the output where the input impedance equals the product of the current gain factor and the emitter resistance. The third configuration is known as common base CB. Here the input current at the emitter almost equals the output current at the collector. The current gain is nearly equal to 1.
The common-base configuration has the lowest current gain among the three basic transistor configurations (common-emitter, common-base, and common-collector). In this configuration, the current gain, often represented as α (alpha), is typically less than 1, as it is defined as the ratio of the output current to the input current. This results in lower overall amplification compared to the other configurations, where the common-emitter and common-collector setups provide higher current gains.
The three basic transistor connection configuration modes are common emitter, common base, and common collector. In the common emitter configuration, the emitter terminal is common to both the input and output circuits, providing high voltage gain. The common base configuration has the base terminal common to both circuits, offering high frequency response but low voltage gain. Finally, the common collector configuration, also known as an emitter follower, provides current gain and high input impedance while maintaining unity voltage gain.
The base is excited by a very low current. That turns the transistor on so that a higher amount of current flow comes out.
The emitter resistor in a common emitter configuration provides negative feedback to the transistor, reducing both its voltage gain and distortion.
output current is emitter current i.e.,Ie
output current is zero
A bipolar transistor can be used in different configurations in linear electronic design. Most well known is the common emitter CE configuration with a base current as input signal resulting in a collector signal multiplied by the current gain factor. The second configuration is known as the emitter follower or common collector configuration. Here the input signal is in the form of a voltage between the base and the common connection. The output signal is found in the form of a voltage at the emitter with a relative low output impedance. The voltage swing at the input is almost as large at the output where the input impedance equals the product of the current gain factor and the emitter resistance. The third configuration is known as common base CB. Here the input current at the emitter almost equals the output current at the collector. The current gain is nearly equal to 1.
comparerission between CB,CC&CE
The common-base configuration has the lowest current gain among the three basic transistor configurations (common-emitter, common-base, and common-collector). In this configuration, the current gain, often represented as α (alpha), is typically less than 1, as it is defined as the ratio of the output current to the input current. This results in lower overall amplification compared to the other configurations, where the common-emitter and common-collector setups provide higher current gains.
The three basic transistor connection configuration modes are common emitter, common base, and common collector. In the common emitter configuration, the emitter terminal is common to both the input and output circuits, providing high voltage gain. The common base configuration has the base terminal common to both circuits, offering high frequency response but low voltage gain. Finally, the common collector configuration, also known as an emitter follower, provides current gain and high input impedance while maintaining unity voltage gain.
the common emitter configuration is most widely used in amplifer circuits because of its high voltage,current & power gain.the common emitter configuration is most widely used in amplifer circuits because of its high voltage,current & power gain.
The base is excited by a very low current. That turns the transistor on so that a higher amount of current flow comes out.
Common Emitter Configuration has maximum impedance.
The emitter resistor in a common emitter configuration provides negative feedback to the transistor, reducing both its voltage gain and distortion.
The common base configuration is not suitable for current amplification primarily because it has a low input impedance and high output impedance, which limits its ability to deliver significant current gain. This configuration typically provides voltage gain but does not amplify current effectively, making it less ideal for applications requiring substantial current amplification. Additionally, the input signal must be applied to the emitter, which can make it less convenient for many circuit designs compared to common emitter or common collector configurations.
The Common Collector configuration amplifies current, by having the emitter voltage follow the base voltage, with an offset of the forward conduction voltage of about 0.7 volts, with a current gain of beta. (hFe)