AD5302/AD5312/AD5322
Rev. D | Page 9 of 24
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 actual endpoints of the DAC transfer
function. A typical INL vs. code plot can be seen in
Figure 6.
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. A typical DNL vs. code plot can be seen
Offset Error
This is a measure of the offset error of the DAC and the output
amplifier. It is expressed as a percentage of the full-scale range.
Gain Error
This is a measure of the span error of the DAC. It is the
deviation 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.
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 the 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.
Analog Crosstalk
This is the glitch impulse transferred to the output of one DAC
due to a change in the output of the other 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 pulsing LDAC low, and monitoring 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
the other 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) while keeping LDAC low
and monitoring the output of the other DAC. The area of the
glitch is expressed in nV-sec.
DC Crosstalk
This is the dc change in the output level of one DAC in response
to a change in the output of the other DAC. It is measured with
a full-scale output change on one DAC while monitoring the
other DAC. It is expressed in μV.
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 dB. VREF is held at 2 V and VDD is varied ±10%.
Reference Feedthrough
This is the ratio of the amplitude of the signal at the DAC
output to the reference input when the DAC output is not being
updated (that is, LDAC is high). It is expressed in dB.
Total Harmonic Distortion (THD)
This is the difference between an ideal sine wave and its
attenuated version using the DAC. The sine wave is used as the
reference for the DAC and the THD is a measure of the
harmonics present on the DAC output. It is measured in dB.
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.
Channel-to-Channel Isolation Definition
This is a ratio of the amplitude of the signal at the output of one
DAC to a sine wave on the reference input of the other DAC. It
is measured in dB.