AD9927 Analog Devices, AD9927 Datasheet - Page 12

• Manufacturer Part Number: AD9927
• Description: 14-Bit CCD Signal Processor
• Manufacturer: Analog Devices

AD9927
TERMINOLOGY
Differential Nonlinearity (DNL)
An ideal ADC exhibits code transitions that are exactly 1 LSB
apart. DNL is the deviation from this ideal value. Therefore, every
code must have a finite width. No missing codes guaranteed to
14-bit resolution indicates that all 16,384 codes, each for its
respective input, must be present over all operating conditions.
Peak Nonlinearity
Peak nonlinearity, a full signal chain specification, refers to the
peak deviation of the output of the AD9927 from a true straight
line. The point used as zero scale occurs 0.5 LSB before the first
code transition. Positive full scale is defined as a level 1 LSB and
0.5 LSB beyond the last code transition. The deviation is measured
from the middle of each particular output code to the true straight
line. The error is then expressed as a percentage of the 2 V ADC
full-scale signal. The input signal is always appropriately gained
up to fill the ADC’s full-scale range.
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Total Output Noise
The rms output noise is measured using histogram techniques.
The standard deviation of the ADC output codes is calculated
in LSB and represents the rms noise level of the total signal
chain at the specified gain setting. The output noise can be
converted to an equivalent voltage using the relationship
where n is the bit resolution of the ADC. For the AD9927,
1 LSB is 0.122 mV.
Power Supply Rejection (PSR)
The PSR is measured with a step change applied to the supply
pins. The PSR specification is calculated from the change in the
data outputs for a given step change in the supply voltage.
1 LSB = (ADC Full Scale/2
n
Codes)