AD7366-5ARUZ AD [Analog Devices], AD7366-5ARUZ Datasheet - Page 10

• Manufacturer Part Number: AD7366-5ARUZ
• Description: True Bipolar Input, Dual 1us, 12-Bit, 2-Channel SAR ADC
• Manufacturer: AD [Analog Devices]

AD7366
TERMINOLOGY
Differential Nonlinearity
Differential nonlinearity is the difference between the measured
and the ideal 1 LSB change between any two adjacent codes in
the ADC.
Integral Nonlinearity
Integral nonlinearity 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 single
(1) LSB point below the first code transition and full scale, a
point 1 LSB above the last code transition.
Zero Code Error
It is the deviation of the midscale transition (all 1s to all 0s)
from the ideal V
ranges and 2×V
Positive Full Scale Error
It is the deviation of the last code transition (011…110) to
(011…111) from the ideal ( +4 × V
LSB) after the Zero Code Error has been adjusted out.
Negative Full Scale Error
This is the deviation of the first code transition (10…000) to
(10…001) from the ideal (i.e., - 4 x V
LSB or AGND + 1LSB) after the Zero Code Error has been
adjusted out.
Zero Code Error Match
This is the difference in zero code error across all 12 channels.
Positive Full Scale Error Match
This is the difference in positive full scale error across all
channels.
Negative Full Scale Error Match
This is the difference in negative full scale error across all
channels.
Track-and-Hold Acquisition Time
The track-and-hold amplifier returns to track mode at the end
of conversion. Track-and-hold acquisition time 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.
Signal to (Noise + Distortion) Ratio
This ratio is the measured ratio of signal to (noise + distortion)
at the output of the A/D converter. The signal is the rms
amplitude of the fundamental. Noise is the sum of all non-
fundamental signals up to half the sampling frequency (f
excluding dc. The ratio is dependent on the number of
quantization levels in the digitization process; the more levels,
REF
IN
−1LSB for the unipolar range.
voltage, i.e., AGND – 1/2 LSB for bipolar
REF
REF
- 1 LSB or + 2 x V
+ 1 LSB, - 2 x V
REF
S
REF
/2),
Rev. PrG | Page 10 of 17
– 1
+ 1
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 12-bit converter, this is 74 dB.
Total Harmonic Distortion (THD)
Total harmonic distortion is the ratio of the rms sum of
harmonics to the fundamental. For the AD7366, 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 is a
noise peak.
Channel-to-Channel Isolation
Channel-to-channel isolation is a measure of the level of
crosstalk between any two channels when operating in the +/-
10 V Range. It is measured by applying a full-scale, 150 kHz
sine wave signal to all unselected input channels and
determining how much that signal is attenuated in the selected
channel with a 50 kHz signal. The figure given is the worst-case
across all four channels for the AD7366. See also Typical
Performance Characteristics.
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, 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 AD7366 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
4
, V
Signal to (Noise + Distortion) = (6.02N + 1.76) dB
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
=
20
S
/2, excluding dc) to the rms value of the
log
Preliminary Technical Data
V
2
2
+
V
3
2
+
V
V
1
4
2
+
V
5
2
+
V
6
2
2
, V
3
,