SR=max
DV
(t)
OUT
Dt
SBAS403D
– JUNE 2007 – REVISED MAY 2011
Gain Temperature Coefficient
Digital Feedthrough
The gain temperature coefficient is defined as the
Digital feedthrough is defined as impulse seen at the
change in gain error with changes in temperature.
output of the DAC from the digital inputs of the DAC.
The gain temperature coefficient is expressed in ppm
It is measured when the DAC output is not updated. It
of FSR/
°C.
is specified in nV-s, and measured with a full-scale
code change on the data bus; that is, from all '0's to
Power-Supply Rejection Ratio (PSRR)
all '1's and vice versa.
Power-supply rejection ratio (PSRR) is defined as the
Channel-to-Channel DC Crosstalk
ratio of change in output voltage to a change in
supply voltage for a full-scale output of the DAC. The
Channel-to-channel dc crosstalk is defined as the dc
PSRR of a device indicates how the output of the
change in the output level of one DAC channel in
DAC is affected by changes in the supply voltage.
response to a change in the output of another DAC
PSRR is measured in decibels (dB).
channel. It is measured with a full-scale output
change on one DAC channel while monitoring
Monotonicity
another DAC channel remains at midscale. It is
expressed in LSB.
Monotonicity is defined as a slope whose sign does
not change. If a DAC is monotonic, the output
Channel-to-Channel AC Crosstalk
changes in the same direction or remains at least
constant for each step increase (or decrease) in the
AC crosstalk in a multi-channel DAC is defined as the
input code.
amount of ac interference experienced on the output
of a channel at a frequency (f) (and its harmonics),
when the output of an adjacent channel changes its
DYNAMIC PERFORMANCE
value at the rate of frequency (f). It is measured with
Dynamic performance parameters are specifications
one channel output oscillating with a sine wave of
such as settling time or slew rate, which are important
1kHz frequency, while monitoring the amplitude of
in applications where the signal rapidly changes
1kHz harmonics on an adjacent DAC channel output
and/or high frequency signals are present.
(kept at zero scale). It is expressed in dB.
Slew Rate
Signal-to-Noise Ratio (SNR)
The output slew rate (SR) of an amplifier or other
Signal-to-noise ratio (SNR) is defined as the ratio of
electronic circuit is defined as the maximum rate of
the root mean-squared (RMS) value of the output
change of the output voltage for all possible input
signal divided by the RMS values of the sum of all
signals.
other spectral components below one-half the output
frequency, not including harmonics or dc. SNR is
measured in dB.
Total Harmonic Distortion (THD)
Where
ΔVOUT(t) is the output produced by the
amplifier as a function of time t.
Total harmonic distortion + noise is defined as the
ratio of the RMS values of the harmonics and noise
Output Voltage Settling Time
to the value of the fundamental frequency. It is
expressed in a percentage of the fundamental
Settling time is the total time (including slew time) for
frequency amplitude at sampling rate fS.
the DAC output to settle within an error band around
its final value after a change in input. Settling times
Spurious-Free Dynamic Range (SFDR)
are specified to within
±0.003% (or whatever value is
specified) of full-scale range (FSR).
Spurious-free dynamic range (SFDR) is the usable
dynamic range of a DAC before spurious noise
Code Change/Digital-to-Analog Glitch Energy
interferes or distorts the fundamental signal. SFDR is
the measure of the difference in amplitude between
Digital-to-analog glitch impulse is the impulse injected
the fundamental and the largest harmonically or
into the analog output when the input code in the
non-harmonically related spur from dc to the full
DAC register changes state. It is normally specified
Nyquist bandwidth (half the DAC sampling rate, or
as the area of the glitch in nanovolts-second (nV-s),
fS/2). A spur is any frequency bin on a spectrum
and is measured when the digital input code is
analyzer, or from a Fourier transform, of the analog
changed by 1LSB at the major carry transition.
output of the DAC. SFDR is specified in decibels
relative to the carrier (dBc).
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2007–2011, Texas Instruments Incorporated