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opamp

I am studying designing circuits. I got a strange problem with LT Spice. I didn't connect any inputs into the amp but the result showed output... I couldn't understand why it had the output voltage. Could you please teach me about a way to get rid of the output when none of inputs?

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You have nothing connected to the op-amp inputs so they are floating and could go to any voltage. Any difference in the two input voltages will be multiplied by the open-loop gain (in the order of 1,000,000) and appear on the output. The surprising thing is that they seem to be quite close in voltage to each other because otherwise the output would be at V+ or ground.

Complete the circuit and then test. At the moment your circuit is useless.

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The op-amp model includes an input leakage current from the supply rails that charges the input and Miller feedback capacitances. Or it could result from an internal current charging the compensation capacitance. Or both.

It would be interesting to use this data to verify specifications in the data sheet.

The nice straight line indicates a current charging a capacitance.

A real circuit would be influenced by electric fields in the vicinity so the effect seen in simulation would be overwhelmed.

As @Transistor indicated, completing the circuit will mitigate the effect.

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