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Open-Loop Gain
The gain of a circuit is its ability to raise the amplitude or power of an input signal. The open-loop gain is the gain of an op-amp when no feedback is applied. In an ideal op-amp, the open-loop gain is infinite. In reality, the open-loop gain for a typical op-amp is around 10 to the power of five, or 100,000.
Voltage Range
In an ideal op-amp, the range of voltages available at the output is deemed to be infinite. In reality, the maximum positive and negative voltages at the output are limited by the supply voltages available to the op-amp.
Infinite Bandwidth
The available bandwidth of an ideal op-amp is infinite. The frequency magnitude response of an ideal op-amp is flat, with zero phase shift. This means that the frequency of the output signal will be exactly the same as the frequency of the input signal, and the waveforms would be exactly synchronized.
Power Bandwidth and Slew Rate
The power bandwidth is the range of frequencies at which full output current and voltage is available. In an ideal op-amp it is assumed to be infinite; that is, full power is available at all frequencies. The slew rate is also assumed to be infinite. In other words, the rate of change of the output voltage is deemed to have no limits.
Input Current and Noise
There is assumed to be no leakage and no bias current into an ideal op-amp. The input current is assumed to be zero. Noise -- extraneous and unwanted interference with the signal -- is also assumed to be zero.
Input and Output Impedance
The input impedance is the opposition that the op-amp presents to the flow of current when a voltage is applied to its inputs. In an ideal op-amp, the input impedance is assumed to be infinite. The impedance at the output is also assumed to be infinite.
Common-Mode Rejection Ratio and Power Supply Rejection Ratio
The common-mode rejection ratio (CMRR) is the tendency of the op-amp to reject input that is the same at both input terminals. The power-supply rejection ratio (PSRR) is the ratio of the rate of change in the op-amp's supply voltage to the differential input voltage that the supply voltage produces in the device. Both are assumed to be infinite in an ideal op-amp.
General
Two important basic concepts can be derived from the various characteristics of the ideal op-amp. First, the differential input voltage is zero. Second, the current flow into either input terminal is also zero. These two properties are fundamental to all op-amp theory and circuit design.