AD5308/AD5318/AD5328
Rev. F | Page 13 of 28
TERMINOLOGY
Relative Accuracy
For the DAC, relative accuracy or integral nonlinearity (INL) is
a measure of the maximum deviation, in LSB, from a straight
line passing through the endpoints of the DAC transfer func-
Differential Nonlinearity
Differential nonlinearity (DNL) is the difference between the
measured change and the ideal 1 LSB change between any two
adjacent codes. A specified differential nonlinearity of ±1 LSB
maximum ensures monotonicity. This DAC is guaranteed
monotonic by design. Typical DNL vs. code plots can be seen
Offset Error
This is a measure of the offset error of the DAC and the output
positive, and is expressed in millivolts.
Gain Error
This is a measure of the span error of the DAC. It is the devia-
tion in slope of the actual DAC transfer characteristic from the
ideal expressed as a percentage of the full-scale range.
Offset Error Drift
This is a measure of the change in offset error with changes in
temperature. It is expressed in (ppm of full-scale range)/°C.
Gain Error Drift
This is a measure of the change in gain error with changes in
temperature. It is expressed in (ppm of full-scale range)/°C.
DC Power Supply Rejection Ratio (PSRR)
This indicates how the output of the DAC is affected by changes
in the supply voltage. PSRR is the ratio of the change in VOUT to
a change in VDD for full-scale output of the DAC. It is measured
in decibels. VREF is held at 2 V and VDD is varied ±10%.
DC Crosstalk
This is the dc change in the output level of one DAC in response
to a change in the output of another DAC. It is measured with a
full-scale output change on one DAC while monitoring another
DAC. It is expressed in microvolts.
Reference Feedthrough
This is the ratio of the amplitude of the signal at the DAC out-
put to the reference input when the DAC output is not being
updated (that is, LDAC is high). It is expressed in decibels.
Channel-to-Channel Isolation
This is the ratio of the amplitude of the signal at the output of
one DAC to a sine wave on the reference input of another DAC.
It is measured in decibels.
Major-Code Transition Glitch Energy
Major-code transition glitch energy is the energy of the impulse
injected into the analog output when the code in the DAC
register changes state. It is normally specified as the area of the
glitch in nV-sec and is measured when the digital code is
changed by 1 LSB at the major carry transition (011 ... 11 to
100 ... 00 or 100 ... 00 to 011 ... 11).
Digital Feedthrough
Digital feedthrough is a measure of the impulse injected into
the analog output of a DAC from the digital input pins of the
device, but is measured when the DAC is not being written to
(SYNC held high). It is specified in nV-sec and is measured
with a full-scale change on the digital input pins, that is, from
all 0s to all 1s and vice versa.
Digital Crosstalk
This is the glitch impulse transferred to the output of one DAC
at midscale in response to a full-scale code change (all 0s to all
1s and vice versa) in the input register of another DAC. It is
measured in standalone mode and is expressed in nV-sec.
Analog Crosstalk
This is the glitch impulse transferred to the output of one DAC
due to a change in the output of another DAC. It is measured by
loading one of the input registers with a full-scale code change
(all 0s to all 1s and vice versa) while keeping LDAC high. Then
pulse LDAC low and monitor the output of the DAC whose digital
code is not changed. The area of the glitch is expressed in nV-sec.
DAC-to-DAC Crosstalk
This is the glitch impulse transferred to the output of one DAC
due to a digital code change and subsequent output change of
another DAC. This includes both digital and analog crosstalk.
It is measured by loading one of the DACs with a full-scale code
change (all 0s to all 1s and vice versa) with LDAC low and
monitoring the output of another DAC. The energy of the glitch
is expressed in nV-sec.
Multiplying Bandwidth
The amplifiers within the DAC have a finite bandwidth. The
multiplying bandwidth is a measure of this. A sine wave on the
reference (with full-scale code loaded to the DAC) appears on
the output. The multiplying bandwidth is the frequency at
which the output amplitude falls to 3 dB below the input.
Total Harmonic Distortion (THD)
This is the difference between an ideal sine wave and its atten-
uated version using the DAC. The sine wave is used as the refer-
ence for the DAC and the THD is a measure of the harmonics
present on the DAC output. It is measured in decibels.