AN2438 Freescale Semiconductor / Motorola, AN2438 Datasheet - Page 3

• Manufacturer Part Number: AN2438
• Description: ADC Definitions and Specifications
• Manufacturer: Freescale Semiconductor / Motorola

Quantization Error (E
MOTOROLA
$7
$6
$5
$4
$3
$2
$1
$0
Conversion
V
REFL
Ideal Straight-Line TF
Ideal Straight-Line
1
Input Voltage in LSB
Transfer Function
2
3
4
5
Q
The way the Ideal transfer function is divided into steps depends on the method
of quantization the ADC uses. The two possible methods are:
) and Method
6
1. Uncompensated Quantization — The first step is taken at 1LSB, with
2. ½LSB Compensated Quantization – The first step is taken at ½LSB,
Freescale Semiconductor, Inc.
7
For More Information On This Product,
V
REFH
each successive step taken at 1LSB intervals and the last step taken at
V
1LSB.
with each successive step taken at 1LSB intervals and the last step
taken at V
±½LSB.
REFH
Figure 1. Quantization Graphs
ADC Definitions and Specifications
$7
$6
$5
$4
$3
$2
$1
$0
Conversion
V
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– 1LSB. The Quantization Error (E
Uncompensated Ideal TF
REFL
Ideal Code
REFH
(1
Width
1
Input Voltage in LSB
LSB
2
)
– 1½LSB. The Quantization Error (E
3
Quantization
(0 to 1
Ideal Transfer
4
Error
Function
5
LSB
6
)
7
V
REFH
$7
$6
$5
$2
$1
$0
Conversion
½
V
Quantization Error (EQ) and Method
LSB
REFL
Ideal Code
Q
(1
Width
1
Input Voltage in LSB
Compensated Ideal TF
) in this case is from 0LSB to
LSB
2
)
Quantization
3
Ideal Transfer
(±½
Error
4
Function
Q
LSB
) in this case is
5
)
6
7
V
AN2438/D
REFH
3