ꢉꢃ ꢠꢡ ꢢ ꢣ ꢤ
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SBAS341B − DECEMBER 2004 − REVISED APRIL 2005
DEFINITIONS
Absolute Input Voltage
Intermodulation Distortion (IMD)
Absolute input voltage, given in volts, is the voltage of each
analog input (AINN or AINP) with respect to AGND.
IMD, given in dB, is measured while applying two input
signals of the same magnitude, but with slightly different
frequencies. It is calculated as the difference between the
rms amplitude of the input signal to the rms amplitude of
the peak spurious signal.
Aperture Delay
Aperture delay is the delay between the rising edge of CLK
and the sampling of the input signal.
Offset Error
Common-Mode Input Voltage
Offset Error, given in % of FSR, is the output reading when
the differential input is zero.
Common-mode input voltage (VCM) is the average voltage
of the analog inputs:
Offset Error Drift
(AINP ) AINN)
Offset error drift, given in ppm of FSR/_C, is the drift over
temperature of the offset error. The offset error is specified
as the larger of the drift from ambient (T = 25_C) to the
minimum or maximum operating temperatures.
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Differential Input Voltage
Differential input voltage (VIN) is the voltage difference
between the analog inputs (AINP−AINN).
Signal-to-Noise Ratio (SNR)
Differential Nonlinearity (DNL)
SNR, given in dB, is the ratio of the rms value of the input
signal to the sum of all the frequency components below
fCLK/2 (the Nyquist frequency) excluding the first six
harmonics of the input signal and the dc component.
DNL, given in least-significant bits of the output code
(LSB), is the maximum deviation of the output code step
sizes from the ideal value of 1LSB.
Signal-to-Noise and Distortion (SINAD)
Full-Scale Range (FSR)
SINAD, given in dB, is the ratio of the rms value of the input
signal to the sum of all the frequency components below
FSR is the difference between the maximum and minimum
measurable input signals (FSR = 2VREF).
f
CLK/2 (the Nyquist frequency) including the harmonics of
Gain Error
the input signal but excluding the dc component.
Gain error, given in %, is the error of the full-scale input
signal with respect to the ideal value.
Spurious-Free Dynamic Range (SFDR)
SFDR, given in dB, is the difference between the rms
amplitude of the input signal to the rms amplitude of the
peak spurious signal.
Gain Error Drift
Gain error drift, given in ppm/_C, is the drift over
temperature of the gain error. The gain error is specified as
the larger of the drift from ambient (T = 25_C) to the
minimum or maximum operating temperatures.
Total Harmonic Distortion (THD)
THD, given in dB, is the ratio of the sum of the rms value
of the first six harmonics of the input signal to the rms value
of the input signal.
Integral Nonlinearity (INL)
INL, given in least-significant bits of the output code (LSB),
is the maximum deviation of the output codes from a best
fit line.
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BB [ BURR-BROWN CORPORATION ]
