The op-amp is said be ideal if it has the following characteristics:
1.Its open-loop gain A if infinite.When an op-amp is operated without any connection between the output and any of the inputs(i.e.,without feedback),it is said to be in the open-loop condition.infinite voltage gain means the voltage difference required between the two inputs to produce any output voltage is zero.
2.Its input resistance(i.e., the resistance measured between inverting and non-inverting terminals) Rin is infinite.It means that the input current (current drawn from the source)is zero and so it does not load the source.It also means that an ideal op-amp is a voltage controlled device.
3.Its output impedance Rout is zero i.e., the output voltage Vout does not depend on the load resistance connected between the output terminals i.e., output voltage Vout is independent of the current drawn by the load.The output thus can drive an infinite number of other devices.
4.perfect balance.Because of infinite voltage gain,the voltage between the inverting and noninverting terminals of input i.e., differential input voltage vd=v2-v1 is essentially zero(i.e.,v1=v2) for finite output voltage Vout. This implies that v1 and v2 track each other i.e., a virtual short circuit exists between the two input terminals but with no current flowing between the two terminals, as Rin is infinite.
5.Infinite frequency bandwidth i.e.,it has flat frequency response from dc to infinity so that any frequency singal from zero to infinity Hz can be amplified without attention.
6.Drift of characteristics with temperature is nil.
7.Common-mode rejection ratio(CMRR) is infinite so that amplifier is free from undesried common-mode signals such as pickup,thermal noise etc.
8.Slew rate is infinite so that output voltage changes occur simultaneously with input voltage changes.
9.Output voltage is zero when input voltage is zero i.e., offset voltage s zero.
Because of having infinite input resistance and zero output resistance, ideal op-amp behaves as an ideal voltage controlled voltage source(VCVS).
To amplify the output of passive waveshaping networks without loading the network and also not affecting the nature of waveform a high gain VCVS with infinite bandwidth is required.An ideal op-amp bears all these characteristics,so it is suitable for such a purpose
1.Its open-loop gain A if infinite.When an op-amp is operated without any connection between the output and any of the inputs(i.e.,without feedback),it is said to be in the open-loop condition.infinite voltage gain means the voltage difference required between the two inputs to produce any output voltage is zero.
2.Its input resistance(i.e., the resistance measured between inverting and non-inverting terminals) Rin is infinite.It means that the input current (current drawn from the source)is zero and so it does not load the source.It also means that an ideal op-amp is a voltage controlled device.
3.Its output impedance Rout is zero i.e., the output voltage Vout does not depend on the load resistance connected between the output terminals i.e., output voltage Vout is independent of the current drawn by the load.The output thus can drive an infinite number of other devices.
4.perfect balance.Because of infinite voltage gain,the voltage between the inverting and noninverting terminals of input i.e., differential input voltage vd=v2-v1 is essentially zero(i.e.,v1=v2) for finite output voltage Vout. This implies that v1 and v2 track each other i.e., a virtual short circuit exists between the two input terminals but with no current flowing between the two terminals, as Rin is infinite.
5.Infinite frequency bandwidth i.e.,it has flat frequency response from dc to infinity so that any frequency singal from zero to infinity Hz can be amplified without attention.
6.Drift of characteristics with temperature is nil.
7.Common-mode rejection ratio(CMRR) is infinite so that amplifier is free from undesried common-mode signals such as pickup,thermal noise etc.
8.Slew rate is infinite so that output voltage changes occur simultaneously with input voltage changes.
9.Output voltage is zero when input voltage is zero i.e., offset voltage s zero.
Because of having infinite input resistance and zero output resistance, ideal op-amp behaves as an ideal voltage controlled voltage source(VCVS).
To amplify the output of passive waveshaping networks without loading the network and also not affecting the nature of waveform a high gain VCVS with infinite bandwidth is required.An ideal op-amp bears all these characteristics,so it is suitable for such a purpose
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