BeginnerTopic 17 of 104Electronics & Embedded
Operational amplifier
High-gain differential amplifier used with feedback to build precise circuits.
In depth
An op-amp has differential inputs, very high open-loop gain (10⁵+), high input and low output impedance. Used with negative feedback to set precise gain. Specs: GBW, slew rate, offset, bias current, CMRR, rail limits.
Key points
- Gain-bandwidth product constant
- Rail-to-rail types
- Offset and drift in precision work
ExampleThe LM741 is the classic general-purpose op-amp; modern ones are faster and quieter.
What is Operational amplifier?
High-gain differential amplifier used with feedback to build precise circuits.
Why is it important to understand operational amplifier?
The op-amp is the most versatile analogue building block, and understanding it is essential for almost any precision analogue circuit.
What are the key op-amp characteristics?
Very high open-loop gain, very high input impedance, low output impedance and a differential input, so it amplifies the voltage difference.
Why does an op-amp need feedback?
Without feedback the open-loop gain is so large that the output saturates, so feedback sets a precise and stable closed-loop gain.
How is Operational amplifier used in practice?
Typical applications include building an instrumentation amplifier for a strain gauge, creating a buffer stage between a sensor and an ADC and designing an active filter for a sensor signal.
What should I learn before Operational amplifier?
Study "Small-signal models" first (topic 16 of 104 in Electronics & Embedded). It covers the groundwork this topic builds on.
What are the key points of Operational amplifier?
Gain-bandwidth product constant. Rail-to-rail types. Offset and drift in precision work.
Can you give an example of Operational amplifier?
The LM741 is the classic general-purpose op-amp; modern ones are faster and quieter.
What comes after Operational amplifier?
The next topic is "Ideal op-amp rules", which builds directly on this one.
How difficult is Operational amplifier?
It is classed as Beginner in Electronics & Embedded (topic 17 of 104). It is an entry-level topic. It relies only on basic school mathematics and the ideas introduced earlier in this discipline.