Data Sheet
AD9832
TERMINOLOGY
Output Compliance
Integral Nonlinearity
The output compliance refers to the maximum voltage that can
be generated at the output of the DAC to meet the specifications.
When voltages greater than those specified for the output
compliance are generated, the AD9832 may not meet the
specifications listed in the data sheet.
This is the maximum deviation of any code from a straight line
passing through the endpoints of the transfer function. The
endpoints of the transfer function are zero scale, a point 0.5 LSB
below the first code transition (000 . . . 00 to 000 . . . 01) and full
scale, a point 0.5 LSB above the last code transition (111 . . . 10
to 111 . . . 11). The error is expressed in LSBs.
Spurious-Free Dynamic Range (SFDR)
Along with the frequency of interest, harmonics of the fundamental
frequency and images of the MCLK frequency are present at the
output of a DDS device. SFDR refers to the largest spur or harmonic
present in the band of interest. The wide-band SFDR gives the
magnitude of the largest harmonic or spur relative to the magnitude
of the fundamental frequency in the bandwidth 2 MHz about
the fundamental frequency. The narrowband SFDR gives the
attenuation of the largest spur or harmonic in a bandwidth of
50 kHz about the fundamental frequency.
Differential Nonlinearity
This is the difference between the measured and ideal 1 LSB
change between two adjacent codes in the DAC.
Signal-to-Noise-and-Distortion Ratio
It is measured signal to noise at the output of the DAC. The
signal is the rms magnitude of the fundamental. Noise is the
rms sum of all the nonfundamental signals up to half the
sampling frequency (fMCLK/2) but excluding the dc component.
The signal-to-noise-and-distortion ratio is dependent on the
number of quantization levels used in the digitization process;
the more levels, the smaller the quantization noise. The theoretical
signal-to-noise-and-distortion ratio for a sine wave input is
Clock Feedthrough
There is feedthrough from the MCLK input to the analog output.
Clock feedthrough refers to the magnitude of the MCLK signal
relative to the fundamental frequency in the output spectrum of
the AD9832.
Signal-to-Noise-and-Distortion = (6.02N + 1.76) dB
where N is the number of bits. Thus, for an ideal 10-bit converter,
the signal-to-noise-and-distortion ratio = 61.96 dB.
Total Harmonic Distortion (THD)
THD is the ratio of the rms sum of harmonics to the rms value of
the fundamental. For the AD9832, THD is defined as
V22 +V32 +V4 +V52 +V62
2
THD = 20log
V
1
where:
V1 is the rms amplitude of the fundamental.
V2, V3, V4, V5, and V6 are the rms amplitudes of the second
through the sixth harmonic.
Rev. E | Page 11 of 28
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