Description of an op amp circuit with a capacitor.
It looks like a comparator with some short-term hysteresis.

At DC, the circuit simplifies to this:







simulate this circuit &ndash; Schematic created using CircuitLab

(Op amp inputs have a very high impedance, so R can be ignored.)

This is just a comparator. If \$V_i &gt; 0\$, the output goes as negative as possible. If \$V_i &lt; 0\$, the output goes as positive as possible.

Adding in the R-C circuit affects the non-inverting input voltage when the output switches.







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When the output switches from negative to positive, it charges up the capacitor through the resistor. This current creates a voltage across the resistor, which boosts the voltage at the non-inverting input. This effectively moves the input threshold, making the circuit more resistance to noise. It won't last very long, but maybe it doesn't have to.

If the circuit is drawn incorrectly and the inverting input was supposed to be on the bottom, then I'd call it a non-inverting integrator. It's definitely not a low-pass filter because there's a capacitor between the output and the feedback terminal. That opens the feedback path at low frequencies, which increases the gain.