Quantization
What is the Quantization?
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There are two main concepts that are involved in
the Conversion of Analog to Digital signals:
Sampling
Sampling as its name suggests can be defined as
take samples. Take samples of a digital signal
over x axis
• Quantization
• The second step assigns a
numerical value to the voltage.
• The discretization of Time is
called sampling and the
discretization of Amplitude is
called quantization
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• The quantizer can’t search over an infinite number of
possibilities and must restrict itself to a limited set of
potential values.
• So essentially the analog-to-digital conversion is a
combination of sampling and quantization
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The size of this set corresponds to the range
of the quantizer and is always a power of 2
Since the value is necessarily contained in the
complete set of 2N potential values
Only N bits are required to represent all the
binary encoded numbers that can be
generated by the quantizer
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ADCs are often referred to as N-bit ADCs, where
N represents the number of bits used by the ADC
to encode its digitized values
the quantization and encoding process cannot be
infinitely accurate and can only provide an
approximation of the real values present the
ADC’s analog input.
The higher the resolution of the quantizer, the
closer this approximation will be to the actual
value of the signal
What is Quantization errors ?
The conversion
process will always
introduce systematic
quantization errors.
 for example, a 4-bit
number can represent 16
voltage levels—from 0 to
15.
 So, the maximum error =
15/(2^4-1)
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• Increase the number of bits to eight,
• The maximum error will be= 15/(2^8-1)