Data Sheet ADDI7100
Rev. D | Page 11 of 20
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 12-bit resolution indicates that all 4096 codes, respectively,
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 ADDI7100 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
that is 1.5 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 gained
appropriately to fill the full-scale range of the ADC.
Total Output Noise
The rms output noise is measured using histogram techniques.
The standard deviation of the ADC output codes is calculated
in LSBs 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
1 LSB = (ADC Full Scale/2
N
codes)
where N is the bit resolution of the ADC. For example, 1 LSB of
the ADDI7100 is 0.5 mV.
Power Supply Rejection (PSR)
PSR is measured with a step change applied to the supply pins.
This represents a very high frequency disturbance on the power
supply of the ADDI7100. The PSR specification is calculated
from the change in the data outputs for a given step change in
the supply voltage.
Internal Delay for SHP/SHD
The internal delay (also called aperture delay) is the time delay
that occurs from the time a sampling edge is applied to the
ADDI7100 until the actual sample of the input signal is held.
Both SHP and SHD sample the input signal during the transi-
tion from low to high; therefore, the internal delay is measured
from the rising edge of each clock to the instant that the actual
internal sample is taken.
