| Electronics > Beginners |
| Common Emitter BJT amp phase |
| (1/2) > >> |
| TheBaconWizard:
I've been looking at common emitter BJT amplifiers and I get the principle in general.. I want voltage amplification hence this choice, and in this case it only needs to be on or off, so saturation-mode. However, all the tutorials I've seen so far tell me that the same waveform is produced whether I use NPN or PNP. It seems to me that they should be the precise inverse of each other? What am I missing? In fact.. if indeed they DO have exactly the same result, how WOULD I produce a signal that is exactly 180deg out of phase compared with these simple amplifiers? Many thanks |
| David Hess:
Common emitter, aka shunt feedback amplifiers, invert the input signal whether NPN or PNP. If you want a non-inverted signal, then you can use a common base or common collector NPN or PNP, use two common emitter amplifiers in series, or maybe add a transformer. |
| TheBaconWizard:
Many thanks |
| vk6zgo:
--- Quote from: David Hess on June 19, 2018, 09:17:03 am ---Common emitter, aka shunt feedback amplifiers, invert the input signal whether NPN or PNP. If you want a non-inverted signal, then you can use a common base or common collector NPN or PNP, use two common emitter amplifiers in series, or maybe add a transformer. --- End quote --- Actually, you would use two CE stages in cascade . Two transistors in series is a very different circuit configuration. |
| David Hess:
--- Quote from: vk6zgo on June 19, 2018, 11:20:22 am --- --- Quote from: David Hess on June 19, 2018, 09:17:03 am ---Common emitter, aka shunt feedback amplifiers, invert the input signal whether NPN or PNP. If you want a non-inverted signal, then you can use a common base or common collector NPN or PNP, use two common emitter amplifiers in series, or maybe add a transformer. --- End quote --- Actually, you would use two CE stages in cascade. Two transistors in series is a very different circuit configuration. --- End quote --- Thanks. Learning or being reminded of something like this is why I participate. A differential pair can also be used and it produces both outputs. |
| Navigation |
| Message Index |
| Next page |