An operational amplifiers (Op-Amp
or Opamp) is a DC-coupled high-gain electronic voltage amplifier. The op-amps
are used to do mathematical operations in many linear, non-linear and
frequency-dependent circuits. An op-amp output voltage is typically hundreds of
thousands of times larger than the voltage difference between its input voltages.
An op-amp consists of five terminals. Two terminals for input consists a
non-inverting input (+) with voltage V+ and an inverting input (–) with voltage
V−. One output terminal, and two terminals for power supply consists of positive
power supply (VS+) and negative power supply (VS−). An ideal op-amp has infinite
input resistance (Ri) and gain (A). Also it has zero input current (iin)
and output resistance (Ro). A realistic op-amp has finite input
resistance and gain. Also it has a non-zero input current and output
resistance. An op-amp has a linear region and two saturated regions. In
saturate region output voltage is equal negative power supply or positive power
supply. When input voltage increases in saturate region, output voltage will be
constant.
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| Figure 1: A Real Inverting Op-Amp |
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| Figure 2: A Real Inverting Op-Amp |
The inverting op-amp gain is negative. Gain = V(out) / V(in) = - (R2/R1)
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| Figure 3: A Real Op-Amp |
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