Closed-loop gain is the voltage gain of an op-amp circuit after feedback is applied. In Electrical Circuits and Systems I, it is the gain you design for, because feedback makes the amplifier more predictable than open-loop operation.
Closed-loop gain is the actual voltage gain of an op-amp circuit when feedback is part of the circuit. In Electrical Circuits and Systems I, this is the gain you usually care about because the feedback network, not the raw op-amp, sets how much the output changes for a given input.
At the simplest level, gain is still output divided by input, so you can write closed-loop gain as A_CL = V_out / V_in. But that ratio only makes sense after the circuit is wired with a feedback path, usually negative feedback, that sends part of the output back to the input. That feedback forces the op-amp to settle at a value that matches the resistor or network values you chose.
This is very different from open-loop gain, where the op-amp is left on its own and the gain is so huge that even a tiny input difference can drive the output into saturation. In a closed-loop configuration, the amplifier behaves more like a controlled tool. You can set gains like 1, 2, 10, or another designed value, and the circuit stays much more linear over a useful range.
That control comes with tradeoffs and benefits. Feedback reduces distortion, improves predictability, and often lowers output impedance, which helps the circuit drive a load more cleanly. It also changes bandwidth and frequency response, so a closed-loop amplifier does not just boost signals, it shapes how the amplifier responds across frequencies.
A common way to think about it is this: the op-amp provides the muscle, while the feedback network sets the rules. If the ideal op-amp assumptions are in play, closed-loop gain is stable and depends on the circuit topology, not on tiny changes in the op-amp itself. If the op-amp is nonideal, the gain can still be close to the designed value, but finite open-loop gain, gain error, and other limits start to show up.
Closed-loop gain is one of the first places op-amp theory turns into circuit design in Electrical Circuits and Systems I. Once you move past ideal characteristics, you need a gain that you can calculate, build, and verify, not one that jumps to the rails the moment the input changes.
This term shows up whenever you analyze an inverting or non-inverting amplifier, compare design choices, or predict whether an op-amp circuit will stay in its linear region. If a homework problem gives resistor values, closed-loop gain is usually the path to finding the output voltage. If a lab asks why the measured output is not exactly what you expected, closed-loop gain is where you start checking for finite open-loop gain effects or gain error.
It also connects directly to how feedback improves a circuit. Instead of treating feedback as just a theory word, closed-loop gain shows what feedback actually does: it turns a high-gain device into a stable amplifier with a chosen transfer behavior. That is the logic behind many of the op-amp circuits you will keep seeing later in the course.
Keep studying Electrical Circuits and Systems I Unit 5
Visual cheatsheet
view galleryOpen-Loop Gain
Open-loop gain is the gain of the op-amp without any feedback applied, and it is usually extremely large. Closed-loop gain is the controlled result after feedback is added, so the two are not interchangeable. In problems, open-loop gain explains why the op-amp can react strongly, while closed-loop gain tells you the value the circuit actually settles to.
Feedback
Feedback is the mechanism that feeds part of the output back to the input and changes how the amplifier behaves. Closed-loop gain is the numerical outcome of that setup. When you see a feedback network in a circuit, you are usually looking for how it sets the gain and keeps the output from running away.
Negative Feedback
Negative feedback subtracts part of the output from the input, which makes the op-amp work in a more controlled region. Most closed-loop op-amp amplifiers in this course use negative feedback because it stabilizes gain and improves linearity. If feedback were positive, the circuit would behave very differently and may not act like a normal amplifier at all.
finite open-loop gain effects
Ideal analysis often assumes the op-amp has infinite open-loop gain, but real devices do not. Finite open-loop gain effects can make the actual closed-loop gain differ slightly from the resistor-based design value, especially when precision matters. This is why measured lab values sometimes miss the textbook answer by a small amount.
A quiz or problem-set question will usually give you an op-amp circuit and ask for the output voltage, the gain, or the resistor ratio needed for a target gain. Your job is to identify the closed-loop configuration, apply the right gain formula, and check whether the circuit should stay in its linear region. If the question includes a real op-amp instead of an ideal one, look for gain error or finite open-loop gain effects that make the answer slightly different from the ideal calculation.
In a lab, you might compare the designed closed-loop gain to the measured gain from a waveform or DC test. If the output clips or saturates, that is a sign the circuit is not staying in the intended closed-loop operating range.
Open-loop gain is the amplifier gain with no feedback, while closed-loop gain is the gain after feedback is added. They are commonly confused because both describe amplification, but only closed-loop gain is usually set by the external circuit design. Open-loop gain is huge and unstable for practical use, while closed-loop gain is predictable and useful.
Closed-loop gain is the voltage gain of an op-amp circuit after feedback is connected.
In most circuit problems, closed-loop gain is the value you design for and calculate from the feedback network.
Negative feedback makes the gain more stable, more linear, and easier to predict than open-loop operation.
The ideal formula gives the expected gain, but real op-amps can show gain error when open-loop gain is finite.
If the output clips or behaves strangely, check whether the circuit is actually operating in a proper closed-loop range.
Closed-loop gain is the voltage gain of an op-amp circuit when feedback is connected. It is the gain the circuit is designed to have, unlike open-loop gain, which is the huge raw gain of the op-amp by itself. In class problems, you usually find it from the feedback network or from Vout divided by Vin.
You often calculate it from the circuit’s feedback topology, such as an inverting or non-inverting op-amp setup. The general idea is still A_CL = V_out / V_in, but the resistor arrangement tells you what that ratio should be. If the problem uses a real op-amp, the measured gain may differ a little from the ideal result.
No. Open-loop gain is the gain without feedback, and it is usually extremely large. Closed-loop gain is the gain after feedback is applied, so it is much more controlled and useful for design. That difference is why feedback is such a big part of op-amp circuit analysis.
Feedback sends part of the output back to the input, which makes the op-amp adjust its output until the circuit reaches the gain set by the external components. In a negative feedback circuit, this makes the output more predictable and less sensitive to the op-amp’s raw internal gain. It also helps reduce distortion and improves linear operation.