AD9708

–5–

REV. B

DEFINITIONS OF SPECIFICATIONS

Linearity Error (Also Called Integral Nonlinearity or INL)

Linearity error is defined as the maximum deviation of the

actual analog output from the ideal output, determined by a

straight line drawn from zero to full scale.

Differential Nonlinearity (or DNL)

DNL is the measure of the variation in analog value, normalized

to full scale, associated with a 1 LSB change in digital input code.

Monotonicity

A D/A converter is monotonic if the output either increases or

remains constant as the digital input increases.

Offset Error

The deviation of the output current from the ideal of zero is

called offset error. For IOUTA, 0 mA output is expected when

the inputs are all 0s. For IOUTB, 0 mA output is expected

when all inputs are set to 1s.

Gain Error

The difference between the actual and ideal output span. The

actual span is determined by the output when all inputs are set

to 1s minus the output when all inputs are set to 0s.

Output Compliance Range

The range of allowable voltage at the output of a current-output

DAC. Operation beyond the maximum compliance limits may

cause either output stage saturation or breakdown resulting in

nonlinear performance.

Temperature Drift

Temperature drift is specified as the maximum change from the

ambient (+25

°C) value to the value at either T

offset and gain drift, the drift is reported in ppm of full-scale

range (FSR) per degree C. For reference drift, the drift is

reported in ppm per degree C.

Power Supply Rejection

The maximum change in the full-scale output as the supplies

are varied from nominal to minimum and maximum specified

voltages.

Settling Time

The time required for the output to reach and remain within a

specified error band about its final value, measured from the

start of the output transition.

Glitch Impulse

Asymmetrical switching times in a DAC give rise to undesired

output transients that are quantified by a glitch impulse. It is

specified as the net area of the glitch in pV-s.

Spurious-Free Dynamic Range

The difference, in dB, between the rms amplitude of the output

signal and the peak spurious signal over the specified bandwidth.

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

S/N+D is the ratio of the rms value of the measured output

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.

Total Harmonic Distortion

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

components to the rms value of the measured output signal. It is

expressed as a percentage or in decibels (dB).

DVDD

DCOM

RETIMED

CLOCK

OUTPUT*

DIGITAL

DATA

TEKTRONIX

AWG-2021

LECROY 9210

PULSE GENERATOR

CLOCK

OUTPUT

50

20pF

50

20pF

TO HP3589A

SPECTRUM/

NETWORK

ANALYZER

50

INPUT

* AWG2021 CLOCK RETIMED

SUCH THAT DIGITAL DATA

TRANSITIONS ON FALLING EDGE

OF 50% DUTY CYCLE CLOCK.

+1.20V REF

REFLO

REF IO

FS ADJ

50pF

COMP1

0.1 F

CURRENT

SOURCE

ARRAY

+5V

AVDD

SEGMENTED

SWITCHES

LATCHES

DVDD

DCOM

CLOCK

SLEEP

IOUTA

IOUTB

COMP2

ACOM

0.1 F

+5V

2k

0.1 F

AD9708

50

Figure 2. Basic AC Characterization Test Setup