I'm going to be honest with you guys. I'm totally green when it comes to electronic, but I need to pass labs (as you do). I was given scheme of what I think (I did some digging) of is Common Emitter Amplifier. My task is to find what is wrong with it and fix it. Could you please help with solving this mystery? Here are screenshots from PSpice.



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    \$\begingroup\$ Hello there, I'm sincerely grateful for your attention and time. The main idea for this is just to work. I'm not sure about the chart, is it correct? I thought it should be more sinusoidal, or that isn't the case. Once more thank you for your time. \$\endgroup\$ – Ament Jan 9 at 20:00
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    \$\begingroup\$ The waveform is highly distorted: however it could be just that you are overdriving the amplifier. Try to reduce progressively the voltage \$V_\mathrm{g}\$ and see what happens. \$\endgroup\$ – Daniele Tampieri Jan 9 at 20:04
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    \$\begingroup\$ I don't need to pass labs but I do teach them. It's important that you try to figure this out for yourself. If you need help you should talk to your instructor. Tell us as much as you know about the circuit. Tell us how you think the circuit is malfunctioning. Ask a very specific question. \$\endgroup\$ – Elliot Alderson Jan 9 at 20:10
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    \$\begingroup\$ Any AC grounded CE amplifier of this topology will distort. The gain varies (a lot) with the collector current and the collector current varies with the signal. You need to either add in local NFB or else use this as part of a larger system and supply some global NFB to fix it. And that's only a problem to worry about only after you get the circuit well-designed. You need to first design it right. But even then, it's still a problem without corrective NFB somewhere. Is your goal a (nearly) fixed gain stage? Or what? What's the context here? Also what is the source? What are you driving? \$\endgroup\$ – jonk Jan 9 at 20:15
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    \$\begingroup\$ Put in 1 milliVoltPP. Examine the output. Repeat this for 1Hz, 10Hz, 100Hz, 1000Hz. Now put in 2 milliVolts. Now put in 4 milliVolts. Now put in 8 milliVolts. Now put in 16milliVolts. And go write the Taylor Series approximation for the diode equation, using the first 2 or 3 terms, to learn about the distortion. By the way, what is the base voltage? the emitter voltage? and the collector voltage? how much collector deltaVoltage can this circuit provide, before distorting or clipping or railing? \$\endgroup\$ – analogsystemsrf Jan 10 at 4:10

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