Ideal Op-Amp (feedback)
An ideal operational amplifier is treated as having infinite open-loop gain and zero input current; closed-loop behavior uses the standard resistor formulas for inverting gain −R_f/R_in, non-inverting gain 1+R_f/R_g, and unity-gain buffering. The page plots input and output versus time for a sine or DC drive and can clip outputs to ±V_sat as a crude saturation model.
Who it's for: Introductory analog electronics after Ohm’s law; pairs with the RC filter and Bode pages.
Key terms
- operational amplifier
- virtual ground
- negative feedback
- voltage follower
- gain
How it works
**Ideal** op-amp: infinite open-loop gain, zero input current, and (when feedback closes the loop) the output follows the classical resistor ratios. Switch among **inverting**, **non-inverting**, and **unity-gain buffer**; drive the input with a sine or a DC level and optionally **clip** the output to ±V_sat.
Key equations
Frequently asked questions
- Where are bandwidth, offset, and input bias current?
- They are omitted on purpose: this is the textbook ideal op-amp used to teach closed-loop gain from passive feedback networks before non-ideal limitations.
- Why can clipping happen if the amp is ideal?
- Infinite gain only applies inside the linear feedback model; the optional rail clip is a stand-in for finite supply voltage and output swing limits.
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