How to make a output amplifier's output swing in +0.5V/-0.5V

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enchanter

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I am learning analog design. about the amplifier, I only got the circuit who's supply voltage is VDD/GND. So the output of that is between VDD and GND. Then how could I design an amplifier with output swing between +0.5V and -0.5V?

Thanks
 

You could use some switched capacitor regulator to create a negative supply... for a very simple solution take a look at MAX1044, so you could supply your opamp with negative voltage. But can you explain better your circuit, there might be better solutions...
 

enchanter said:
... how could I design an amplifier with output swing between +0.5V and -0.5V?
Click to expand...
If your amplifier provides an output swing of 1Vpp, you can couple it via a series capacitor to an output load resistor to GND. This will result in your required output swing - that's rather trivial, of course ;-) .
 

Thats a solution just for specific applications... imagin an imput of a constant value, and he is using the opamp as a buffer, the output would go to 0 at any constant value.....

Just a questions.. is it a design of an IC or a circuit?
 

Sink0 said:
Thats a solution just for specific applications... imagin an imput of a constant value, and he is using the opamp as a buffer, the output would go to 0 at any constant value.....
Click to expand...
Very true: not a good solution for a BGA, LDO, or any ref.voltage output. But didn't enchanter ask for a solution for "an amplifier with output swing between +0.5V and -0.5V"? It's still the simplest solution for swing frequencies > 1/2πRC , isn't it? Still, I told that's trivial ;-)
 

thanks for your reply. Sorry for my ignorant. I can't find a supply voltage +0.9V and -0.9V for that amp. You know all I learned from the book are the circuits with supply voltage with +1V and ground. No negative supply voltage and negative output. So I am not sure is it that simple to get the negative output by replace GND with -0.9V supply?. Maybe some can give me a simple circuit with have negative output to make me have a little sense on that.

Thanks.
 

Yes you can. As long as you are referring everything to the same ground.
All you have in a circuit is voltage differences. You can operate the same circuit with 2V and 0V(GND) or 1V and -1V. If in the first case the circut can have an output from 200mV to 1.8V, then in the latter case the same circuit can have an output from -800mV to 800mV. This now with respect to the same ground, with respect to which the negative supply is -1V.
 

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