MAX1136_09 Datasheet, PDF (20/22 Pages) Maxim Integrated Products – 2.7V to 3.6V and 4.5V to 5.5V, Low-Power, 4-/12-Channel, 2-Wire Serial 10-Bit ADCs

2.7V to 3.6V and 4.5V to 5.5V, Low-Power,
4-/12-Channel, 2-Wire Serial 10-Bit ADCs
Effective Number of Bits
Effective number of bits (ENOB) indicates the global
accuracy of an ADC at a specific input frequency and
sampling rate. An ideal ADC’s error consists of quanti-
zation noise only. With an input range equal to the
ADC’s full-scale range, calculate the ENOB as follows:
SINAD(dB)
=
20
×
⎡
log_⎢
⎣
SignalRMS
NoiseRMS + THDRMS
⎤
⎥
⎦
ENOB = (SINAD - 1.76)/6.02
Total Harmonic Distortion
Total harmonic distortion (THD) is the ratio of the RMS
sum of the input signal’s first five harmonics to the fun-
damental itself. This is expressed as:
⎛
THD
=
20
×
log
⎜
⎜
⎝⎜
⎛
⎝⎜⎜
V₂₂
+
V₃₂ + V₄₂
V₁
+
V₅₂
⎞
⎠⎟⎟
⎞
⎟
⎟
⎠⎟
where V₁ is the fundamental amplitude, and V₂ through V₅
are the amplitudes of the 2nd through 5th order harmonics.
Spurious-Free Dynamic Range
Spurious-free dynamic range (SFDR) is the ratio of RMS
amplitude of the fundamental (maximum signal compo-
nent) to the RMS value of the next largest distortion
component.
20 ______________________________________________________________________________________