Op-Amps, Feedback, and Analog Signal Conditioning
Precision Analog Building Blocks
Why op-amps are useful
An operational amplifier is a high-gain differential amplifier. With negative feedback, it can perform stable and predictable tasks such as amplification, buffering, summing, filtering, and comparison. Ideal-op-amp rules are powerful approximations for many beginner and intermediate designs.
Ideal op-amp rules
Feedback intuition
Negative feedback reduces gain but improves linearity, bandwidth usefulness, and predictability. In many circuits, that tradeoff is exactly what you want.
What does negative feedback generally do in an op-amp circuit?
Negative feedback trades raw gain for controlled, stable behavior.
Correct answer: Improves linear control and stability
In the ideal op-amp model, what is the input current?
Ideal op-amp inputs draw no current.
Correct answer: zero
A voltage follower is mainly used as a
A follower provides high input impedance and low output impedance, so it buffers one stage from the next.
Correct answer: Buffer
What happens when an op-amp output tries to exceed its supply rails?
A real op-amp cannot output beyond its supply limits, so it clips or saturates.
Correct answer: it saturates
Analyzing a feedback amplifier
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Step 1: Identify the feedback path and input configuration.
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Step 2: Apply the ideal op-amp assumptions if valid.
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Step 3: Solve for closed-loop gain from the resistor network.
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Step 4: Check that the output stays within supply limits.
Common op-amp uses
Inverting amplifier
- Output is phase-reversed
- Gain set by resistor ratio
Non-inverting amplifier
- Input applied to non-inverting terminal
- High input impedance and positive gain