Data Sheet
AD9737A/AD9739A
Rev. | Page 39 of 64
TERMINOLOGY
Linearity Error (Integral Nonlinearity or INL)
The maximum deviation of the actual analog output from the
ideal output, determined by a straight line drawn from 0 to full
scale.
Differential Nonlinearity (DNL)
The measure of the variation in analog value, normalized to full
scale, associated with a 1 LSB change in digital input code.
Monotonicity
A DAC 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 0 is called
the offset error. For IOUTP, 0 mA output is expected when the
inputs are all 0s. For IOUTN, 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 output when all inputs are set
to 1 minus 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 may
cause either output stage saturation or breakdown, resulting in
nonlinear performance.
Temperature Drift
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 °C. For reference drift, the drift is reported in ppm per °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.
Spurious-Free Dynamic Range
The difference, in decibels (dB), between the rms amplitude of
the output signal and the peak spurious signal over the specified
bandwidth.
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. It is expressed as
a percentage or in decibels (dB).
Noise Spectral Density (NSD)
NSD is the converter noise power per unit of bandwidth. This is
usually specified in dBm/Hz in the presence of a 0 dBm full-
scale signal.
Adjacent Channel Leakage Ratio (ACLR)
The adjacent channel leakage (power) ratio is a ratio, in dBc, of
the measured power within a channel relative to its adjacent
channels.
Modulation Error Ratio (MER)
Modulated signals create a discrete set of output values referred
to as a constellation. Each symbol creates an output signal
corresponding to one point on the constellation. MER is a measure
of the discrepancy between the average output symbol magnitude
and the rms error magnitude of the individual symbol.
Intermodulation Distortion (IMD)
IMD is the result of two or more signals at different frequencies
mixing together. Many products are created according to the
formula, aF1 ± bF2, where a and b are integer values.
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