The op amp is an electronic unit that behaves like a voltage-controlled voltage source. An op amp may also be regarded as a voltage amplifier with very high gain. It can also be used in making a voltage- or current-controlled current source.
An op amp is an active circuit element designed to perform mathematical operations of addition, subtraction, multiplication, division, differentiation, and integration.
The five important terminals:
- Inverting input, pin 2.
- Non-inverting input, pin 3.
- Output, pin 6.
- Positive power supply \(V^{+}\), pin 7.
- Negative power supply \(V^{-}\), pin 4.
An input applied to the non-inverting terminal will appear with the same polarity at the output, while an input applied to the inverting terminal will appear inverted at the output.
Powering the Op Amp
\(\displaystyle i_{o} = i_{1} + i_{2} + i_{+} + i_{-}\)
The output voltage \(v_{o}\) of op amp is dependent on and is limited by the supply voltage \(V_{CC}\). Op amp can operate in three modes, depending on the differential input voltage \(v_{d}\).
- Positive saturation, \(v_{o} = V_{CC}\).
- Linear region, \(-V_{CC} \le v_{o} \le V_{CC}\).
- Negative saturation, \(v_{o} = -V_{CC}\).
Applications
The op amp is a fundamental building block in modern electronic instrumentation. It is used extensively in many devices, along with resistors and other passive elements. Its numerous practical applications include instrumentation amplifiers, digital-to-analog converters, analog computers, level shifters, filters, calibration circuits, inverters, summers, integrators, differentiators, subtractors, logarithmic amplifiers, comparators, gyrators, oscillators, rectifiers, regulators, voltage-to-current converters, current-to-voltage converters, and clippers.