Common Base Amplifier

431

04:51:42

The input impedance is about 2Ω and the output load is 1kΩ which gives a voltage gain of about 500V/V. With an input voltage of 2.1mV the output is 1V. The current gain is around 0.9A/A. The input has a peak current of 1.11mA and the output has a peak current of 1mA.

I’ve always thought the common base amplifier was a little strange. Its operation just seemed weird to me. It doesn’t amplify current, and when it does amplify the voltage the input impedance is much lower than the output impedance. I guess it’s useful if you need to transform a low voltage and low impedance signal to a high voltage and high impedance signal, but I don’t know how common such a situation would be. For something like audio amplification it is typically a low voltage and low current signal from a microphone which would be amplified first with common emitter to boost the voltage and then with common collector to drive a speaker. If anyone knows any applications for these, please let me know. I’d like to know what these are used for, if anything.

published 5 years ago

PrathikP

5 years ago

Your circuit doesn't seem to need 5.6mF of capacitance at the input. 220uF seems to do the trick.

slm67

5 years ago

very interesting solution 👍

jason9

5 years ago

Yes, for 1kHz, but looking at the bode plot the 5.6mF cap is needed for less than 3dB voltage drop at 20Hz.

PrathikP

5 years ago

Ah ok

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