ADAQ7980 datasheet(21/45 Pages) AD

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Data Sheet

ADAQ4381-4

TERMINOLOGY

analog.com

Rev. 0 | 21 of 45

Long-Term Drift (ΔVOUT_LTD)

Long-term drift refers to the shift in the output voltage vs. time. This

is expressed as a difference in ppm from the nominal output.

∆VOUT_LTD= VOUTt1−VOUTt0

VOUTt0

×106 (7)

where:

ΔVOUT_LTD is expressed in ppm.

VOUT(t0) is the output voltage at the starting time of the

measurement.

VOUT(t1) is the output voltage at the end time of the measurement.

Thermal Hysteresis (ΔVOUT_HYS)

Thermal hysteresis represents the change in the output voltage

after the device is exposed to a specified temperature cycle. This is

expressed as a difference in ppm from the nominal output.

∆VOUT_HYS= VOUT1_25°C−VOUT2_25°C

VOUT1_25°C

×106 (8)

where:

ΔVOUT_HYS is expressed in ppm.

VOUT1_25°C is the output voltage at 25°C.

VOUT2_25°C is the output voltage after temperature cycling.

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 decibels.

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 decibels.

Signal-to-Noise-and-Distortion (SINAD) Ratio

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

the rms sum of all other spectral components that are less than

the Nyquist frequency, including harmonics but excluding DC. The

value for SINAD is expressed in decibels.

Effective Number of Bits (ENOB)

ENOB is a measurement of the resolution with a sine wave input.

ENOB is related to SINAD as follows:

ENOB=SINADdB−1.76

6.02

(9)

where ENOB is expressed in bits.

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.

Common-Mode Rejection Ratio (CMRR)

CMRR is the ratio of the power in μModule output at the frequency,

f, to the power of a 100 mV p-p sine wave applied to the input

common-mode voltage of frequency, f.

CMRRdB =10logPμModule_IN/PμModule_OUT (10)

where:

PμModule_IN is the common-mode power at the frequency, f, applied

to the inputs.

PμModule_OUT is the power at the frequency, f, in the μModule output.

Power-Supply Rejection Ratio (PSRR)

PSRR is the ratio of the power in the μModule output at the

frequency, f, to the power of a 500 mV p-p sine wave applied to

the VS+, REFIN, and IN_LDO supply voltage centered at 5 V of

frequency, f.

PSRRdB =10logPμModule_IN/PμModule_OUT (11)

where:

PμModule_IN is the power at the frequency, f, at the VS+, REFIN, and

IN_LDO pins.

PμModule_OUT is the power at the frequency, f, at the μModule output.

Aperture Delay

Aperture delay is the measure of the acquisition performance and

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

signal is held for a conversion.

Aperture Jitter

Aperture jitter is the variation in aperture delay.

ADAQ7980 Datasheet(PDF) 21 Page - Analog Devices

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