M1AFS250-FGG256I Actel Corporation, M1AFS250-FGG256I Datasheet - Page 104

• Manufacturer Part Number: M1AFS250-FGG256I
• Description: Actel Fusion Family Of Mixed Signal Fpgas
• Manufacturer: Actel Corporation

Device Architecture
2- 88
Terminology
BW is a range of frequencies that a Channel can handle.
A channel is define as an analog input configured as one of the Prescaler range shown in
page
Channel Gain is a measured of the deviation of the actual slope from the ideal slope. The slope is
measured from the 20% and 80% point.
Channel Gain Error is a deviation from the ideal slope of the transfer function. The Prescaler Gain Error
is expressed as the percent difference between the actual and ideal, as shown in
Channel Offset error is measured as the input voltage that causes the transition from zero to a count of
one. An Ideal Prescaler will have offset equal to ½ of LSB voltage. Offset error is a positive or negative
when the first transition point is higher or lower than ideal. Offset error is expressed in LSB or input
voltage.
Total Channel Error is defined as the total error measured compared to the ideal value. Total Channel
Error is the sum of gain error and offset error combined.
measured.
Total Channel Error is defined as the difference between the actual ADC output and ideal ADC output. In
the example shown in
Figure 2-69 • Total Channel Error Example
BW – Bandwidth
Channel
Channel Gain
Channel Gain Error
Channel Input Offset Error
Total Channel Error
2-132. The channel includes the Prescaler circuit and the ADC.
Figure
2-69, the Total Channel Error would be a negative number.
Channel Input
Offset Error
Error
Input Voltage to Prescaler
Gain
Gain
R e visio n 1
=
=
(1-Gain) 100%
Gain
------------------------ -
Gain
T otal C hannel Er r or
actual
ideal
Figure 2-69
×
C hannel G ain
Actual Output
shows how Total Channel Error is
EQ
2.
Table 2-54 on
EQ 1
EQ 2