Single Supply

[vinod_sat]

Hello All,

I only have a single supply to work with. But I have AC signals that I have as inputs to operational amplifiers and comparators.

Could you please suggest how I can achieve results.

Thank you,

Vinod

 

[Papabravo]

If we had any idea what you are trying to do it would be much easierto help you. The general idea is to use V/2 as your reference point or pseudo-ground. Then AC couple the signals. You were going to do that anyway -- right?

 

[vinod_sat]

Thanks for the reply and for the suggestion. I am working on an AC-DC converter and I want to sense AC current through an inductor and force the inductor current to follow a sinusoidal reference.

I would like to accomplish this using analog cicuitry. I will try to create a pseudo ground to accomplish this. Thanks again

 

[audioguru]

Any opamp will work amplifying AC signals if it is capacitor-coupled and uses a filtered half-supply-voltage divider as its voltage reference like this:

 

[vinod_sat]

Thanks for the suggestion. I have few more questions and I would be glad if you can help.

If I have few opamps and comparators that will have to be used for my open loop (say a summer, inv amp and a comparator), looks like I will have to provide a voltage reference for each and every circuit then.

What will I have to do if I use a comparator with a single supply, if I have to compare a sine wave from the output of the summer and a ramp signal.

Thanks again.

 

[audioguru]

You can have a number of DC coupled opamp circuits in series with a single supply if you bias the non-inverting input of the 1st one to half the supply voltage with a resistor divider, then keep all levels within the input common-mode range of the opamps.

A comparator with a single supply can be DC coupled to the sine-wave and triangle-wave signals if they are biased properly and are also powered from the single supply.