AD7357 Analog Devices, AD7357 Datasheet - Page 11

• Manufacturer Part Number: AD7357
• Description: Differential Input, Dual, Simultaneous Sampling, 4.25 MSPS, 14-Bit, SAR ADC
• Manufacturer: Analog Devices

Specifications of AD7357

• Resolution (bits): 14bit
• # Chan: 2
• Sample Rate: 4.25MSPS
• Interface: Ser,SPI
• Analog Input Type: Diff-Bip,Diff-Uni,Usr-Defined Range/Offset
• Ain Range: Vcm ± Vref/2
• Adc Architecture: SAR
• Pkg Type: SOP

Intermodulation Distortion (IMD)
With inputs consisting of sine waves at two frequencies, fa
and fb, any active device with nonlinearities creates distortion
products at 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. 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 AD7357 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, while 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 as per the THD specification (see Table 2), 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 (dB).
Rev. B | Page 11 of 20
Thermal Hysteresis
Thermal hysteresis is defined as the absolute maximum change
of the reference output voltage after the device is cycled through
temperature from either
It is expressed in ppm using the following equation:
where:
V
V
T_HYS–.
REF
REF
(25°C) is V
(T_HYS) is the maximum change of V
T_HYS+ = 25°C to T
T_HYS– = 25°C to T
V
HYS
(
ppm
REF
)
=
at 25°C.
V
REF
(
MIN
MAX
25
°
to 25°C
V
to 25°C
C
REF
)
−
(
V
25
REF
°
C
(
T
)
_
REF
HYS
at T_HYS+ or
)
×
AD7357
10
6