AD7490 Analog Devices, AD7490 Datasheet - Page 11

• Manufacturer Part Number: AD7490
• Description: 16-Channel, 1MSPS, 12-Bit ADC with Sequencer in 28-Lead TSSOP
• Manufacturer: Analog Devices

Specifications of AD7490

• Resolution (bits): 12bit
• # Chan: 16
• Sample Rate: 1MSPS
• Interface: Ser,SPI
• Analog Input Type: SE-Uni
• Ain Range: Uni (Vref),Uni (Vref) x 2
• Adc Architecture: SAR
• Pkg Type: CSP,SOP

Peak Harmonic or Spurious Noise
Peak harmonic or spurious noise is defined as the ratio of the
rms value of the next largest component in the ADC output
spectrum (up to f
fundamental. Normally, the value of this specification is
determined by the largest harmonic in the spectrum, but for
ADCs where the harmonics are buried in the noise floor, it is a
noise peak.
Intermodulation Distortion
With inputs consisting of sine waves at two frequencies, fa
and fb, any active device with nonlinearities creates distortion
products at the sum and difference frequencies of mfa ± nfb,
where m, n = 0, 1, 2, 3, and so on. Intermodulation distortion
terms are those for which neither m nor n are equal to zero.
S
/2 and excluding dc) to the rms value of the
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For example, the second order terms include (fa + fb) and
(fa − fb), while the third order terms include (2fa + fb), (2fa − fb),
(fa + 2fb) and (fa − 2fb).
The AD7490 is tested using the CCIF standard where two input
frequencies near the top end of the input bandwidth are used.
In this case, the second order terms are usually distanced in
frequency from the original sine waves, and the third order
terms are usually at a frequency close to the input frequencies.
As a result, the second and third order terms are specified
separately. The calculation of the intermodulation distortion is
per the THD specification, where it is the ratio of the rms sum
of the individual distortion products to the rms amplitude of
the sum of the fundamentals expressed in decibels.
AD7490