Electronic – Understanding class A amplifier waveforms


I am working on an audio amplifier but got stuck on to a basic of npn transistor circuit.

Attaching a class-A amplifier circuit. Take a look here or here. I tried to simulate the circuit but as everywhere on net it is said that this can amplify whole sine wave , in my P Spice simulation it is not. Only one half of input signal is getting amplified.

My question is how I can get full sine wave (as all the schematic of class a amplifier over the internet claims)? Also please explain why exactly I am getting attached waveform in my circuit.

PSpice Schematic
Output WaveForm

Best Answer

The 10 K and 1 K resistors you have connected to the base of the transistor are for biasing, however, the voltage source you have for the oscillator is preventing that from happening. If you AC couple the oscillator instead (add a capacitor between the signal generator and transistor) you should see correct operation. With the voltages you have you will see distortion (clipping), try reducing the oscillator to 1 V.

You can experiment with the ratio of the biasing resistors to how that influences the output waveform.