Hi guys, I am working on a common emitter amplifier for a lab experiment. It seems to be working but I'm getting a distorted output waveform and don't understand why.
First of all, here is my schematic.
Ce = 338 uF
Cc1 = 20 uF
Cc2 = 8 uF
The output voltage is taken across the 1k load resistor near Cc2. My design specs said to create an amplifier that has a 5 volt peak to peak ac swing on the output. So I used the characteristics from the curve tracer and selected an operating point Q that meets these specs. Below is a screenshot of the operating point.
From this I figured out all the resistors necessary to get me to that operating point and did so successfully. Made all my measurements and the dc bias is pretty much perfect.
Now I applied the small signal ac sinusoid which is to be amplified. Below is a screenshot from the oscilloscope of what I got.
As you see the output is 180 degrees out of phase with the input like its supposed to be. Its also more or less as large as its supposed to be with a gain of around 50. But its very distorted. I don't understand why. I spent half the day trying to figure this out and ended up nowhere.
Can anyone please give me some clues as to what might be wrong here?
First of all, here is my schematic.
Ce = 338 uF
Cc1 = 20 uF
Cc2 = 8 uF
The output voltage is taken across the 1k load resistor near Cc2. My design specs said to create an amplifier that has a 5 volt peak to peak ac swing on the output. So I used the characteristics from the curve tracer and selected an operating point Q that meets these specs. Below is a screenshot of the operating point.
From this I figured out all the resistors necessary to get me to that operating point and did so successfully. Made all my measurements and the dc bias is pretty much perfect.
Now I applied the small signal ac sinusoid which is to be amplified. Below is a screenshot from the oscilloscope of what I got.
As you see the output is 180 degrees out of phase with the input like its supposed to be. Its also more or less as large as its supposed to be with a gain of around 50. But its very distorted. I don't understand why. I spent half the day trying to figure this out and ended up nowhere.
Can anyone please give me some clues as to what might be wrong here?
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