How to design emitter biased BJT amplifier

  Here emitter biased BJT amplifier is designed using the online BJT amplifier design calculator. Emitter biasing method is one of several biasing method for BJT(Bipolar Junction Transistor).

The circuit diagram of a BJT amplifier designed using emitter biasing method is shown below.

In the above circuit, the emitter resistor RE is used as feedback resistor. When the collector current increases, the voltage across RE increases which then reduces the base voltage and thus the base current. As such the function of RE is to stabilize the output current by opposing the increase of output collector current. 

In the circuit above, V1 is the ac signal source say of 10mV and frequency of 1KHz. The dc voltage is VCC which is say 5V. The resistors RB, RC and RE dc biases the BJT transistor. The input signal is coupled into the dc biased circuit using the coupling capacitor C1. Similarly, the amplified signal at the collector is coupled into the load resistor say 10KOhm using another coupling capacitor C2. The capacitor C3 is the bypass capacitor which also is used to stabilize the biased circuit when there is ac signal in the circuit.

We will use the online BJT amplifier design calculator to get the values for the resistors RB, RC and RE and also the coupling capacitors C1 and C2 and the bypass capacitor C3.

 In this example we have used dc beta of 100 and Vbe of 0.75V.

With the obtained resistor and capacitor value the circuit diagram with component values is shown below.

The graph of input ac signal and amplified signal is shown below.

See other similar tutorials:

- How to bias a BJT using voltage divider biasing

- How to Design Collector-Emitter Feedback biased  BJT Amplifier

- How to bias a BJT using base bias

- How to design emitter biased BJT amplifier

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