inverting-amplifiernon-invertingoperational-amplifier
Both the inverting amplifier and non-inverting amplifier use negative feedback. Both provide gain. But one inverts the signal while the other does not. How to know which one to use? Are there applications where only one of the two can be used (provides both positive and negative supplies exist)?
Is it true that single supply op amp can only create non-inverting amplifier?
The inverting configuration is capable of gains less that 1, and can be used as a mixer. Here is a good primer.
http://chrisgammell.com/2008/08/02/how-does-an-op-amp-work-part-1/
I don't know exactly why (anyone feel free to chime in), but the fact that negative feedback is holding the negative input terminal at 0v means that node is a proper place to sum currents, making the mixer circuit viable (although inverting). Op amps are also cheap and come in packages with more than one, so you can usually just invert something again if it's "upside down"
If the resistors making up the voltage divider are of low enough value, and the supply rails are sufficiently low impedance, yes, a single resistor divider can be used to provide virtual ground to multiple op amps.
In order to stiffen up the ground a bit, a capacitor may be added between the supply and ground rails at the resistive divider, and a second capacitor between the virtual ground point and either of the rails.
simulate this circuit – Schematic created using CircuitLab
Alternatively, a dedicated virtual ground IC such as the Texas Instruments precision rail splitter TLE2426 comes in handy for the purpose.
Best Answer
There are a couple reasons (at least) for choosing a particular configuration:
If you need a high input impedance, then you are forced into a non-inverting configuration. This is commonly required in a buffering situation. An inverting configuration has an input impedance equal to the input resistor which may load the source circuit.
If you need a summing amplifier, then inverting is the way to go as the inverting input is the summing junction.
No. With a DC offset (on the non-inverting input) you can have an inverting configuration although the input signal will need to be ac coupled under most circumstances.