AD7484BSTZ Analog Devices Inc, AD7484BSTZ Datasheet - Page 9

• Manufacturer Part Number: AD7484BSTZ
• Description: IC ADC 14BIT SAR 3MSPS 48-LQFP
• Manufacturer: Analog Devices Inc

Specifications of AD7484BSTZ

• Data Interface: Parallel
• Number Of Bits: 14
• Sampling Rate (per Second): 3M
• Number Of Converters: 1
• Power Dissipation (max): 90mW
• Voltage Supply Source: Analog and Digital
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP
• Resolution (bits): 14bit
• Sampling Rate: 3MSPS
• Input Channel Type: Single Ended
• Supply Voltage Range - Analog: 4.75V To 5.25V
• Supply Voltage Range - Digital: 4.75V To 5.25V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: EVAL-AD7484CBZ - BOARD EVALUATION FOR AD7484
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

TERMINOLOGY
Integral Nonlinearity
This is the maximum deviation from a straight line passing
through the endpoints of the ADC transfer function. The
endpoints of the transfer function are zero scale, a point 1/2 LSB
below the first code transition, and full scale, a point 1/2 LSB
above the last code transition.
Differential Nonlinearity
This is the difference between the measured and ideal 1 LSB
change between any two adjacent codes in the ADC.
Offset Error
This is the deviation of the first code transition (00…000) to
(00…001) from the ideal, i.e., AGND + 0.5 LSB.
Gain Error
This is the deviation of the last code transition (111…110) to
(111…111) from the ideal, i.e., V
error has been adjusted out.
Track-and-Hold Acquisition Time
It is the time required for the output of the track-and-hold
amplifier to reach its final value, within ±1/2 LSB, after the end
of conversion (the point at which the track-and-hold returns to
track mode).
Signal-to-(Noise + Distortion) Ratio
This is the measured ratio of signal-to-(noise + distortion) at
the output of the ADC. The signal is the rms amplitude of the
fundamental. Noise is the sum of all nonfundamental signals up
to half the sampling frequency (f
dependent on the number of quantization levels in the
digitization process; the more levels, the smaller the
quantization noise. The theoretical signal-to-(noise + distortion)
ratio for an ideal N-bit converter with a sine wave input is given
by
Thus, for a 14-bit converter, this is 86.04 dB.
Signal
−
to
−
(
Noise
+
Distortion
REF
S
/2), excluding dc. The ratio is
− 1.5 LSB, after the offset
)
=
(
. 6
02
N
+
. 1
76
)
dB
Rev. A | Page 9 of 20
Total Harmonic Distortion (THD)
THD is the ratio of the rms sum of the harmonics to the
fundamental. For the AD7484, it is defined as
where V
V
sixth harmonics.
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 will
be a noise peak.
Intermodulation Distortion
With inputs consisting of sine waves at two frequencies, fa and
fb, any active device with nonlinearities will create distortion
products at sum and difference frequencies of mfa ± nfb, where
m and 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 AD7484 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-order and third-order terms are
specified separately. The calculation of the intermodulation
distortion is as 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 dBs.
4
, V
THD
5
, and V
1
is the rms amplitude of the fundamental and V
( )
dB
6
are the rms amplitudes of the second through the
=
S
20
/2 and excluding dc) to the rms value of the
log
V
2
2
+
V
3
2
+
V
V
4
1
2
+
V
5
2
+
V
6
AD7484
2
2
, V
3
,