
Op amps needs dual supply in order to get a full output swing from its input fed signal, here’s a good app note from Analog Devices on powering op amps using only a single supply.
Battery-powered op amp applications such as those
found in automotive and marine equipment have only a
single available power source. Other applications, such
as computers, may operate from the ac power lines but
still have only a single polarity power source, such as
5 V or 12 V dc. Therefore, it is often a practical necessity
to power op amp circuits from a single polarity supply.
But single supply operation does have its drawbacks: it
requires additional passive components in each stage
and, if not properly executed, can lead to serious instability problems.
