MAX1064 Datasheet, PDF (18/20 Pages) Maxim Integrated Products – 400ksps, +5V, 8-/4-Channel, 10-Bit ADCs with +2.5V Reference and Parallel Interface

400ksps, +5V, 8-/4-Channel, 10-Bit ADCs
with +2.5V Reference and Parallel Interface
SUPPLIES
+3V
V_LOGIC = +3V/+5V GND
R* = 5Ω
4.7µF
0.1µF
V_DD
GND
COM
+3V/+5V DGND
MAX1060
MAX1064
DIGITAL
CIRCUITRY
*OPTIONAL
Figure 11. Power-Supply and Grounding Connections
Signal-to-Noise Plus Distortion
Signal-to-noise plus distortion (SINAD) is the ratio of the
fundamental input frequency’s RMS amplitude to the
RMS equivalent of all other ADC output signals.
SINAD (dB) = 20 x log (Signal_RMS / Noise_RMS)
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 error consists of quantiza-
tion noise only. With an input range equal to the ADC’s
full-scale range, calculate the ENOB as follows:
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 _


V₂ ²
+ V₃₂
+ V₄₂
+
V₅
2


/

V_{1}
Signal-to-Noise Ratio
For a waveform perfectly reconstructed from digital sam-
ples, signal-to-noise ratio (SNR) is the ratio of the full-
scale analog input (RMS value) to the RMS quantization
error (residual error). The ideal theoretical minimum ana-
log-to-digital noise is caused by quantization error only
and results directly from the ADC’s resolution (N bits):
SNR = (6.02 x N + 1.76)dB
In reality, there are other noise sources besides quanti-
zation noise, including thermal noise, reference noise,
clock jitter, etc. Therefore, SNR is computed by taking
the ratio of the RMS signal to the RMS noise, which
includes all spectral components minus the fundamen-
tal, the first five harmonics, and the DC offset.
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 the
RMS amplitude of the fundamental (maximum signal
component) to the RMS value of the next-largest distor-
tion component.
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