# How to Design Collector-Emitter Feedback biased BJT Amplifier

Collector-Emitter Feedback bias method is one of the many biasing method for Bipolar Junction Transistor(BJT) based amplifier. Here we illustrate how to design a BJT amplifier using collector emitter feedback bias method. We will use the online to calculate the resistor and capacitor values. The designed BJT amplifier is then simulated in multisim circuit simulation software.

For construction and real time testing see Construction of Collector-Emitter Feedback Bias BJT Amplifier Test with PC Oscilloscope.

The following shows the circuit diagram of a BJT amplifier designed using collector emitter feedback bias.

In the above circuit, V1 is the ac signal source. Let the amplitude and frequency of the V1 be 10mV and 1KHz. The transistor Q1 has DC beta of 100, Vbe of 0.75V. Let the DC source voltage Vcc be 5V. The resistors RB, RC and RE are used to bias the transistor Q1. Here both collector feedback and emitter feedback is used in order to stabilize the Q-point. The resistor RB is connected from the collector back to the base and this is what causes collector feedback. Similarly, the resistor RE is used to create an emitter feedback to the base. Because we have used both the collector and emitter feedback the circuit is called collector emitter feedback bias. In other to couple the input ac signal into the biased BJT circuit without disturbing the bias point the coupling capacitor C1 is used. Similarly, the amplified output signal at the collector is coupled to the load resistor using capacitor C2. The emitter resistor RE is bypassed using the bypass capacitor C3 to stabilize the bias point.

To calculate the resistors RB, RC, RE values, the coupling capacitors C1 and C2 values and the bypass capacitor C3 value we will use the online BJT amplifier design calculator. Consider that the load resistor RL is 10KOhm.

Using the calculated values in multisim we get the following circuit.

The following graph shows the input signal vin and the output signal vout,

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