Datasheet AD9281 (Analog Devices) - 6

AD9281 AVDD DRVDD AVDD AVDD AVDD AVDD DRVSS DRVSS AVSS AVSS AVSS AVSS AVSS
a. D0–D9 b. Three-State Standby c. CLK
AVDD AVDD AVDD AVDD AVDD REFBS IN AVSS AVDD AVSS AVSS REFBF AVSS AVSS AVSS
d. INA, INB e. Reference f. REFSENSE g. VREF Figure 2. Equivalent Circuits
OFFSET ERROR
scale. Gain error is the deviation of the actual difference be- The first transition should occur at a level 1 LSB above “zero.” tween first and last code transitions and the ideal difference Offset is defined as the deviation of the actual first code transi- between the first and last code transitions. tion from that point.
GAIN MATCH OFFSET MATCH
The change in gain error between I and Q channels. The change in offset error between I and Q channels.
PIPELINE DELAY (LATENCY) EFFECTIVE NUMBER OF BITS (ENOB)
The number of clock cycles between conversion initiation and For a sine wave, SINAD can be expressed in terms of the num- the associated output data being made available. New output ber of bits. Using the following formula, data is provided every rising clock edge. N = (SINAD – 1.76)/6.02
MUX SELECT DELAY
It is possible to get a measure of performance expressed as N, The delay between the change in SELECT pin data level and the effective number of bits. valid data on output pins. Thus, effective number of bits for a device for sine wave inputs at a given input frequency can be calculated directly from its
POWER SUPPLY REJECTION
measured SINAD. The specification shows the maximum change in full scale from the value with the supply at the minimum limit to the value
TOTAL HARMONIC DISTORTION (THD)
with the supply at its maximum limit. THD is the ratio of the rms sum of the first six harmonic com- ponents to the rms value of the measured input signal and
APERTURE JITTER
is expressed as a percentage or in decibels. Aperture jitter is the variation in aperture delay for successive samples and is manifested as noise on the input to the A/D.
SIGNAL-TO-NOISE RATIO (SNR)
SNR is the ratio of the rms value of the measured input signal
APERTURE DELAY
to the rms sum of all other spectral components below the Aperture delay is a measure of the Sample-and-Hold Amplifier Nyquist frequency, excluding the first six harmonics and dc. (SHA) performance and is measured from the rising edge of the The value for SNR is expressed in decibels. clock input to when the input signal is held for conversion.
SPURIOUS FREE DYNAMIC RANGE (SFDR) SIGNAL-TO-NOISE AND DISTORTION (S/N+D, SINAD)
The difference in dB between the rms amplitude of the input
RATIO
signal and the peak spurious signal. S/N+D is the ratio of the rms value of the measured input sig- nal to the rms sum of all other spectral components below
GAIN ERROR
the Nyquist frequency, including harmonics but excluding dc. The first code transition should occur for an analog value 1 LSB The value for S/N+D is expressed in decibels. above nominal negative full scale. The last transition should occur for an analog value 1 LSB below the nominal positive full REV. F –5–