AD9822 데이터 시트보기 (PDF) - Analog Devices

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AD9822

Complete 14-Bit CCD/CIS Signal Processor

Analog Devices 

AD9822

TERMINOLOGY

Integral Nonlinearity (INL)

Integral nonlinearity error refers to the deviation of each

individual code from a line drawn from zero scale through

positive full scale. The point used as zero scale occurs ½ LSB

before the first code transition. Positive full scale is defined as a

level 1 ½ 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)

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 16384 codes,

respectively, must be present over all operating ranges.

Offset Error

The first ADC code transition should occur at a level ½ LSB

above the nominal zero-scale voltage. The offset error is the

deviation of the actual first code transition level from the ideal

level.

Gain Error

The last code transition should occur for an analog value

1 ½ LSB below the nominal full-scale voltage. Gain error is the

deviation of the actual difference between the first and last code

transitions and the ideal difference between the first and last

code transitions.

Input Referred Noise

The rms output noise is measured using histogram techniques.

The ADC output codes’ standard deviation is calculated in LSB

and converted to an equivalent voltage, using the relationship

1 LSB = 4 V/16384 = 244 mV. The noise is then referred to the

input of the AD9822 by dividing by the PGA gain.

Channel-to-Channel Crosstalk

In an ideal 3-channel system, the signal in one channel will not

influence the signal level of another channel. The channel-to-

channel crosstalk specification is a measure of the change that

occurs in one channel as the other two channels are varied. In

the AD9822, one channel is grounded and the other two

channels are exercised with full-scale input signals. The

change in the output codes from the first channel is measured

and compared with the result when all three channels are

grounded. The difference is the channel-to-channel crosstalk,

stated in LSB.

Aperture Delay

The time delay that occurs from when a sampling edge is

applied to the AD9822 until the actual sample of the input

signal is held. Both CDSCLK1 and CDSCLK2 sample the input

signal during the transition from high to low; therefore, the

aperture delay is measured from each clock’s falling edge to the

instant the actual internal sample is taken.

Power Supply Rejection

It specifies the maximum full-scale change that occurs from

the initial value when the supplies are varied over the

specified limits.

Rev. B | Page 8 of 20

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