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AD9216-105PCB

10-Bit, 65/80/105 MSPS Dual A/D Converter

Analog Devices 

AD9216

TERMINOLOGY

Aperture Delay

Aperture delay is a measure of the sample-and-hold amplifier

(SHA) performance and is measured from the rising edge of the

clock input to when the input signal is held for conversion.

Aperture Jitter

The variation in aperture delay for successive samples, which is

manifested as noise on the input to the A/D converter.

Integral Nonlinearity (INL)

INL 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 1/2 LSB before the first

code transition. Positive full scale is defined as a level 1 1/2

LSB beyond the last code transition. The deviation is measured

from the middle of each particular code to the true straight line.

Differential Nonlinearity (DNL, No Missing Codes)

An ideal ADC exhibits code transitions that are exactly 1 LSB

apart. DNL is the deviation from this ideal value. Guaranteed

no missing codes to 10-Bits resolution indicates that all 2048

codes must be present over all operating ranges.

Offset Error

The major carry transition should occur for an analog value 1/2

LSB below VIN+ = VIN- . Offset error is defined as the

deviation of the actual transition from that point.

Gain Error

The first code transition should occur at an analog value 1/2

LSB above negative full scale. The last transition should occur

at an analog value 1 1/2 LSB below the nominal full scale.

Gain error is the deviation of the actual difference between first

and last code transitions and the ideal difference between first

and last code transitions.

Temperature Drift

The temperature drift for zero error and gain error specifies the

maximum change from the initial (25°C) value to the value at

TMIN or TMAX.

Power Supply Rejection

The specification shows the maximum change in full scale

from the value with the supply at the minimum limit to the

value with the supply at its maximum limit.

Total Harmonic Distortion (THD)

The ratio of the rms sum of the first six harmonic components

to the rms value of the measured input signal, expressed as a

percentage or in decibels relative to the peak carrier signal

(dBc).

Preliminary Technical Data

Signal-to-Noise and Distortion (S/N+D, SINAD) Ratio

The ratio of the rms value of the measured 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 decibels relative to the peak carrier

signal (dBc).

Effective Number of Bits (ENOB)

Using the following formula:

ENOB = (SINAD − 1.76) 6.02

effective number of bits for a

device for sine wave inputs at a given input frequency can be

calculated directly from its measured SINAD.

Signal-to-Noise Ratio (SNR)

The ratio of the rms value of the measured input signal to the

rms sum of all other spectral components below the Nyquist

frequency, excluding the first six harmonics and dc. The value

for SNR is expressed in decibels relative to the peak carrier

signal (dBc).

Spurious Free Dynamic Range (SFDR)

The difference in dB between the rms amplitude of the input

signal and the peak spurious signal.

Nyquist Sampling

When the frequency components of the analog input are below

the Nyquist frequency (fCLOCK/2), this is often referred to as

Nyquist sampling.

IF Sampling

Due to the effects of aliasing, an ADC is not necessarily limited

to Nyquist sampling. Higher sampled frequencies will be

aliased down into the first Nyquist zone (DC - fCLOCK/2) on the

output of the ADC. Care must be taken that the bandwidth of

the sampled signal does not overlap Nyquist zones and alias

onto itself. Nyquist sampling performance is limited by the

bandwidth of the input SHA and clock jitter (jitter adds more

noise at higher input frequencies).

Two-Tone SFDR

The ratio of the rms value of either input tone to the rms value

of the peak spurious component. The peak spurious component

may or may not be an IMD product.

Out-of-Range Recovery Time

Out-of-range recovery time is the time it takes for the A/D

converter to reacquire the analog input after a transient from

10% above positive full scale to 10% above negative full scale,

or from 10% below negative full scale to 10% below positive

full scale.

Rev. PrD

Page 10 of 20

6/15/2004

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