8- and 4-Channel, 3 ꢀ ꢁREF
Multirange Inputs, Serial 14-Bit ADCs
2/MAX103
Effective Number of Bits (ENOB)
SCLK
(MODE 0)
ENOB indicates the global accuracy of an ADC at a
specific input frequency and sampling rate. With an
input range equal to the ADC’s full-scale range, calcu-
late the ENOB as follows:
14
15
13
SCLK
(MODE 1)
16
11
15
10
SINAD − 1.76
⎛
⎞
ENOB =
⎜
⎝
⎟
⎠
INTCLK
(MODE 2)
6.02
12
Total Harmonic Distortion (THD)
For the MAX1032/MAX1033, THD is the ratio of the
RMS sum of the input signal’s first four harmonic com-
ponents to the fundamental itself. This is expressed as:
t
AJ
t
AD
SAMPLE INSTANT
HOLD
ANALOG INPUT
TRACK AND HOLD
⎛
⎞
⎟
⎟
⎠
TRACK
2
2
2
2
V
+ V + V + V
3 4 5
2
⎜
THD = 20 × log
⎜
⎝
V
Figure 21. Aperture Diagram
1
where V is the fundamental amplitude, and V through
1
2
V
are the amplitudes of the 2nd- through 5th-order
harmonic components.
5
Spurious-Free Dynamic Range (SFDR)
SFDR is the ratio of RMS amplitude of the fundamental
(maximum signal component) to the RMS value of the
next-largest spectral component.
______________________________________________________________________________________ 29
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
