AD7684BRMZ View Datasheet(PDF) - Analog Devices

Part Name

Description

MFG CO.

AD7684BRMZ

16-Bit, 100 kSPS PulSAR, Differential ADC in MSOP

Analog Devices 

AD7684

TERMINOLOGY

Integral Nonlinearity Error (INL)

Linearity error 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

(see Figure 21).

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

Zero error is the difference between the ideal midscale voltage,

that is, 0 V, and 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 the 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 SINAD by the following formula

ENOB = (SINADdB − 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.

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 (SINAD)

SINAD 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

SINAD is expressed in dB.

Aperture Delay

Aperture delay is a measure of the acquisition performance and

is the time between the falling edge of the CS input and when

the input signal is held for a conversion.

Transient Response

Transient response is the time required for the ADC to accurately

acquire its input after a full-scale step function is applied.

Rev. A | Page 8 of 16

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