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AD9773

PRELIMINARY TECHNICAL DATA

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, deter-

mined 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 in-

creases.

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 cur-

rent-output DAC. Operation beyond the maximum

compliance limits may cause either output stage satu-

ration or breakdown, resulting in nonlinear perfor-

mance.

Temperature Drift

Temperature drift is specified as the maximum change

from the ambient (+25°C) value to the value at either

TMIN or TMAX. For 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 minimum to maximum speci-

fied 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.

Total Harmonic Distortion

THD is the ratio of the rms sum of the first six har-

monic components to the rms value of the measured

fundamental. It is expressed as a percentage or in deci-

bels (dB).

Signal-to-Noise Ratio (SNR)

S/N is the ratio of the rms value of the measured out-

put signal to the rms sum of all other spectral com-

ponents below the Nyquist frequency, excluding the

first six harmonics and dc. The value for SNR is ex-

pressed in decibels.

Interpolation Filter

If the digital inputs to the DAC are sampled at a mul-

tiple rate of fDATA (interpolation rate), a digital filter

can be constructed which has a sharp transition band

near fDATA/2. Images which would typically appear

around fDAC (output data rate) can be greatly supressed.

Passband

Frequency band in which any input applied therein

passes unattenuated to the DAC output.

Stopband Rejection

The amount of attenuation of a frequency outside the

passband applied to the DAC, relative to a full-scale

signal applied at the DAC input within the passband.

Group Delay

Number of input clocks between an impulse applied at

the device input and peak DAC output current. A half-

band FIR filter has constant group delay over its entire

frequency range

Impulse Response

Response of the device to an impulse applied to the

input.

Adjacent Channel Power Ratio (or ACPR)

A ratio in dBc between the measured power within a

channel relative to its adjacent channel.

Complex Modulation

The process of passing the real and imaginary compo-

nents of a signal through a complex modulator (trans-

fer function = e

ωt = cosωt+jsinωt) and realizing real

and imaginary components on the modulator output.

Complex Image Rejection

In a traditional two part upconversion, two images are

created around the second IF frequency. These images

are redundant and have the effect of wasting transmit-

ter power and system bandwidth. By placing the real

part of a second complex modulator in series with the

first complex modulator, either the upper or lower

frequency image near the second IF can be rejected.

REV. PrA

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