CHAPTER 13 A/D CONVERTER
User’s Manual U16896EJ2V0UD
392
(3) Quantization
error
When analog values are converted to digital values, a
±
1/2 LSB error naturally occurs. In an A/D converter, an
analog input voltage in a range of
±
1/2 LSB is converted to the same digital code, so a quantization error
cannot be avoided.
Note that the quantization error is not included in the overall error, zero-scale error, full-scale error, integral
linearity error, and differential linearity error in the characteristics table.
Figure 13-13. Quantization Error
0……0
1……1
Digital output
Quantization error
1/2 LSB
1/2 LSB
Analog input
0
AV
REF0
(4) Zero-scale
error
This shows the difference between the actual measurement value of the analog input voltage and the
theoretical value (1/2 LSB) when the digital output changes from 0……000 to 0……001.
Figure 13-14. Zero-Scale Error
111
011
010
001
Zero-scale error
Ideal line
000
0
1
2
3
AV
REF0
Digital output (Lo
w
er 3 bits)
Analog input (LSB)
-1
100