The input voltage of an operational amplifier (op-amp) refers to the voltage difference between the two input terminals, called the inverting input (-) and the non-inverting input (+).
Op-amps are designed to amplify the difference between these two input voltages. This difference is known as the differential input voltage.
The input voltage can be any value within the op-amp's operating range, which is typically defined by its power supply rails.
For example, if an op-amp is powered by a +15V and -15V supply, its input voltage range would be between -15V and +15V.
The op-amp's output voltage is determined by the input voltage and the open-loop gain, which is a very large value. This means that even a small difference in input voltage can result in a significant output voltage.
To control the output voltage, feedback is typically used. Feedback allows the op-amp to function as a variety of circuits, such as amplifiers, filters, oscillators, and comparators.
Examples:
- Inverting Amplifier: The inverting input is used for signal input, and the non-inverting input is grounded. The output voltage is an amplified and inverted version of the input voltage.
- Non-inverting Amplifier: The non-inverting input is used for signal input, and the inverting input is connected to a feedback network. The output voltage is an amplified and non-inverted version of the input voltage.
Practical Insights:
- The input voltage of an op-amp is a crucial parameter in determining its operation and output characteristics.
- Understanding the relationship between input voltage, open-loop gain, and feedback is essential for designing and analyzing op-amp circuits.
