M1AFS600-PQ208 Datasheet, PDF (121/334 Pages) Microsemi Corporation – Fusion Family of Mixed Signal FPGAs

Fusion Family of Mixed Signal FPGAs
INL – Integral Non-Linearity
INL is the deviation of an actual transfer function from a straight line. After nullifying offset and gain
errors, the straight line is either a best-fit straight line or a line drawn between the end points of the
transfer function (Figure 2-85).
INL = +0.5 LSB
Ideal Output
Actual Output
INL = +1 LSB
Input Voltage to Prescaler
Figure 2-85 • Integral Non-Linearity (INL)
LSB – Least Significant Bit
In a binary number, the LSB is the least weighted bit in the group. Typically, the LSB is the furthest right
bit. For an ADC, the weight of an LSB equals the full-scale voltage range of the converter divided by 2^N,
where N is the converter’s resolution.
EQ 13 shows the calculation for a 10-bit ADC with a unipolar full-scale voltage of 2.56 V:
1 LSB = (2.56 V / 2¹⁰) = 2.5 mV
EQ 13
No Missing Codes
An ADC has no missing codes if it produces all possible digital codes in response to a ramp signal
applied to the analog input.
Offset Error
Offset error indicates how well the actual transfer function matches the ideal transfer function at a single
point. For an ideal ADC, the first transition occurs at 0.5 LSB above zero. The offset voltage is measured
by applying an analog input such that the ADC outputs all zeroes and increases until the first transition
occurs (Figure 2-86 on page 2-106).
Revision 4
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