I have a digital 3.3V PWM signal that I want to send to a speaker, i.e.
- amplify to higher voltage (e.g. 12V, but not sure)
- and remove DC offset with a capacitor.
For the capacitor to work as intended, I think the amplification needs to be capable of sinking to ground.
After all I read, a push-pull amplifier should be doing the trick, but I don’t see how this can work without a negative supply rail. What are my alternatives?
- Since 12V > 3.3V, Q1 will essentially always be in saturation, thus in the configuration above, I’ll have a short circuit if Q2 is also in saturation.
- If I exchange Q1 & Q2, then I won't have the voltage amplification any more, because as soon as C1 reaches 2.7V, the NPN transistor will be cut off. (And if it were not, soon after the PNP transistor would activate again.)