AD9927BBCZ datasheet(12/100 Pages) AD

12 / 100 page

AD9927

Rev. 0 | Page 12 of 100

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.

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

1 LSB = (ADC Full Scale/2n Codes)

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.

AD9927BBCZ Datasheet(PDF) 12 Page - Analog Devices