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|Home Mathematics A/D Conversion|
|See also: Sampling Theorem|
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The analog signal is continuous in time and it is necessary to convert this to a flow of digital values. It is therefore required to define the rate at which new digital values are sampled from the analog signal. The rate of new values is called the sampling rate or sampling frequency of the converter.
On the other hand, it is not only the time which is sampled, it is also the signal which is converted to discrete values. An n-bit ADC (A/D converter) provides 2n discrete quantization levels corresponding to some specified analog input signal amplitude range.
A continuously varying bandlimited signal sampled at a specific frequency can be reproduced from the discrete-time values by an interpolation formula. The accuracy is however limited by quantization error which depends on the amplitude resolution of the converter. However, this faithful reproduction is only possible if the sampling rate is higher than twice the bandwidth of the signal. This is essentially what is embodied in the Shannon-Nyquist sampling theorem.