An operational amplifier, or op-amp, is an integrated circuit used to amplify voltage signals. It has a high input impedance and a low output impedance, allowing it to efficiently amplify weak electrical signals. The basic configuration of an op-amp includes two input terminals (inverting and non-inverting) and one output terminal. The op-amp amplifies the difference in voltage between the two input terminals and outputs a voltage signal that is typically many times larger than the input signal, depending on the gain set by the external components.

An op-amp is a versatile electronic component symbolized by a triangle with two inputs and one output. The inverting input is marked with a minus sign (-), and the non-inverting input is marked with a plus sign (+). The output is usually at the tip of the triangle, opposite the base where the inputs are located. This symbol represents the fundamental operation of the op-amp: it amplifies the voltage difference between the inverting and non-inverting inputs and provides an amplified output.

Internally, an op-amp consists of multiple stages of amplification, including differential amplifiers, voltage gain stages, and an output stage. The differential amplifier at the input stage amplifies the difference between the inverting and non-inverting inputs while rejecting any common-mode signals. The voltage gain stages provide additional amplification, and the output stage ensures low output impedance and sufficient current driving capability. These internal components work together to provide the high gain and stable performance characteristic of op-amps.

Op-amp gain refers to the ratio of the output voltage to the input voltage. The gain of an op-amp can be controlled by external resistors and capacitors in various configurations, such as inverting, non-inverting, and differential amplifier setups. In the inverting configuration, the gain is determined by the ratio of the feedback resistor to the input resistor, resulting in a negative gain. In the non-inverting configuration, the gain is determined by the ratio of the feedback resistor to the resistor connected to the ground, plus one, resulting in a positive gain. The gain can be very high, allowing for significant amplification of the input signal.

An ideal op-amp is a theoretical device with infinite open-loop gain, infinite input impedance, and zero output impedance. It perfectly amplifies the voltage difference between its input terminals without any limitations. In practice, this means the ideal op-amp will amplify the difference between the inverting and non-inverting inputs with no offset, noise, or distortion. Additionally, the ideal op-amp has an infinite bandwidth, allowing it to amplify signals of any frequency without attenuation. Real-world op-amps approximate these ideal characteristics but have limitations due to practical manufacturing constraints.