Single and Split Supply from 1 PSU... Possible?

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If you are using a chipamp that uses a single supply (V+ and ground) -something like the LM384 and wanted to use an op amp on it's front end (say for example for something like a high pass filter), is it possible to power everything from a single PSU?

I can't seem to figure out a way to get the ground reference of the op amp and chip amp at the same potential.
The simplest way would be a single supply op-amp circuit. You would reference the op-amp at 1/2 the supply voltage for its "ground" reference and AC couple the input/output of the op-amp.

If you google "single supply op-amp" or similar there are plenty of hits. TI has a paper titled "A Single-Supply Op-Amp Circuit Collection" that has examples of single supply op-amp circuits (mixers/filters/simple amplifiers etc.) showing half supply connection.

The half-supply voltage reference would probably be a potential divider. You would need to make sure the potential divider on the supply has filter capacitors on the output so you don't end up with poor power supply rejection due to the reference voltage moving around with the supply.

If you split the supply, the signal ground for the chipamp's reference and the op amp's reference will be at different potentials and current will flow right? I tried putting a series cap in between the 2 reference points but it did not work. I know if you just use the V+ rail and the virtual ground to power the chipamp, it will work but you're limiting the power to the chipamp by half which is kind of a waste of time. If something that has been suggested so far will work I'm sorry, I'm just not getting it.
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Try something like this to generate a negative rail. C2, D5 and D6 produce the rail. C3 is the negative rail reservoir cap. V1 is the single winding mains transformer.

You would need to add a negative rail regulator such as a 7912 to give a stable and clean output.




  • Negative Rail.asc
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