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The difference is in the usage. The basic internal configuation of an operational amplifier and a comparator is the same, except the comparator is designed to have as much gain as possible.
An amplifier is intended to produce an output that is proportional to the input. Usually, we want an amplifier to preserve the character of the input signal - we just want the amplifier to give us a higher voltage or current representation of the input.
A comparator has a very high open loop gain and differential inputs. Because the gain is so high, a slight difference in the voltage or current between the inputs will cause the output to "go to the rail" - or in other words when there is a difference between the inputs, the output jumps to the maximum supply voltage. The comparator gets its name because it is comparing the input to zero - if the input is not zero, the output goes to maximum positive or negative supply voltage depending on whether the positive or negative input is greater.
The basic difference between the comparator and the amplifier is that the amplifier amplifies the input signal or changes its amplitude level with minimum distortion of original signal but the job of comparator is to compare the two signals and give the indicationt so that we can know which signal has more strength.
Comparator: Compare input signal with some reference and output of comparator will tell you whether input signal is higher or lower then reference. e.g. Temperature controller.
Amplifier: Is used to increase the strength of the signal. E.g. Microphone of Public Address system receives voice of the person, amplify it and feed to loud speakers so that it can reach to large audience.
Both of them can be constructed with and without operational amplifiers as explained by other forum members above.
Basically, they are the same.
Comparator is an amplifier that is not compensated. We mainly focuses on minimizing the offset voltage and speed when designing an opamp for comparator purpose.
In the high speed system,
@1:
The comparator is generally multi-stage to increase the gain and enhance the resolution .
The amplifier is single or two stage to easy the compensation.
@2:
The comparator is not needed to be compensation, but the amplifier is needed.
@3:
The positive feedback is used in comparator to increase the speed, but the amplifier is used in the negative feedback to avoid the oscillation.
@4:
Basically, the amplifier is responsing with small signal, but the comparator is large signal response. Thus, the region of transistors is different.
The basic difference between the comparator and opamp is that the output stage of the comparator is designed in such a way that it operates in the saturation region and for the opamp the output stage is designed such that it operates in the linear region.
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