AD7694 datasheet(8/28 Pages) AD

8 / 28 page

AD7688

Rev. A | Page 8 of 28

TERMINOLOGY

Integral Nonlinearity Error (INL)

It refers to the deviation of each individual code from a line

drawn from negative full scale through positive full scale. The

point used as negative full scale occurs ½ LSB before the first

code transition. Positive full scale is defined as a level 1½ LSB

beyond the last code transition. The deviation is measured from

the middle of each code to the true straight line (Figure 25).

Differential Nonlinearity Error (DNL)

In an ideal ADC, code transitions are 1 LSB apart. DNL is the

maximum deviation from this ideal value. It is often specified in

terms of resolution for which no missing codes are guaranteed.

Zero Error

It is the difference between the ideal midscale voltage, that is, 0

V, from the actual voltage producing the midscale output code,

that is, 0 LSB.

Gain Error

The first transition (from 100 . . . 00 to 100 . . . 01) should occur

at a level ½ LSB above nominal negative full scale (−4.999924 V

for the ±5 V range). The last transition (from 011…10 to

011…11) should occur for an analog voltage 1½ LSB below the

nominal full scale (+4.999771 V for the ±5 V range.) The gain

error is the deviation of the difference between the actual level

of the last transition and the actual level of the first transition

from the difference between the ideal levels.

Spurious-Free Dynamic Range (SFDR)

SFDR is the difference, in decibels (dB), between the rms

amplitude of the input signal and the peak spurious signal.

Effective Number of Bits (ENOB)

ENOB is a measurement of the resolution with a sine wave

input. It is related to S/(N+D) by the following formula

ENOB = (S/[N + D]dB − 1.76)/6.02

and is expressed in bits.

Total Harmonic Distortion (THD)

THD is the ratio of the rms sum of the first five harmonic

components to the rms value of a full-scale input signal and is

expressed in dB.

Dynamic Range

It is the ratio of the rms value of the full scale to the total rms

noise measured with the inputs shorted together. The value for

dynamic range is expressed in dB.

Signal-to-Noise Ratio (SNR)

SNR is the ratio of the rms value of the actual input signal to the

rms sum of all other spectral components below the Nyquist

frequency, excluding harmonics and dc. The value for SNR is

expressed in dB.

Signal-to-(Noise + Distortion) Ratio (S/[N+D])

S/(N+D) is the ratio of the rms value of the actual input signal

to the rms sum of all other spectral components below the

Nyquist frequency, including harmonics but excluding dc. The

value for S/(N+D) is expressed in dB.

Aperture Delay

Aperature delay is the measure of the acquisition performance.

It is the time between the rising edge of the CNV input and

when the input signal is held for a conversion.

Transient Response

It is the time required for the ADC to accurately acquire its

input after a full-scale step function was applied.

AD7694 Datasheet(PDF) 8 Page - Analog Devices

AD7694 Datasheet(HTML) 8 Page - Analog Devices

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

Datasheet Download

Link URL