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AD9122

Rev. 0 | Page 16 of 56

TERMINOLOGY

Integral Nonlinearity (INL)

INL is defined as the maximum deviation of the actual analog

output from the ideal output, determined by a straight line drawn

from zero scale to full scale.

Differential Nonlinearity (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.

Offset Error

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

called offset error. For IOUT1P, 0 mA output is expected when

the inputs are all 0s. For IOUT1N, 0 mA output is expected

when all inputs are set to 1.

Gain Error

The difference between the actual and ideal output span. The

actual span is determined by the difference between the output

when all inputs are set to 1 and the output when all inputs are

set to 0.

Output Compliance Range

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

DAC. Operation beyond the maximum compliance limits can

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 TMIN or TMAX.

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

scale range (FSR) per degree Celsius. For reference drift, the

drift is reported in ppm per degree Celsius.

Power Supply Rejection (PSR)

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

are varied from minimum to maximum specified voltages.

Settling Time

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

specified error band around its final value, measured from

the start of the output transition.

Spurious Free Dynamic Range (SFDR)

The difference, in decibels, between the peak amplitude of the

output signal and the peak spurious signal within the dc to the

Nyquist frequency of the DAC. Typically, energy in this band is

rejected by the interpolation filters. This specification, therefore,

defines how well the interpolation filters work and the effect of

other parasitic coupling paths to the DAC output.

Signal-to-Noise Ratio (SNR)

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

for SNR is expressed in decibels.

Interpolation Filter

If the digital inputs to the DAC are sampled at a multiple rate of

fDATA (interpolation rate), a digital filter can be constructed that

has a sharp transition band near fDATA/2. Images that typically

appear around fDAC (output data rate) can be greatly suppressed.

Adjacent Channel Leakage Ratio (ACLR)

The ratio in decibels relative to the carrier (dBc) between the

measured power within a channel relative to its adjacent channel.

Complex Image Rejection

In a traditional two-part upconversion, two images are created

around the second IF frequency. These images have the effect

of wasting transmitter 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.

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