MAX1284 Maxim, MAX1284 Datasheet - Page 14

• Manufacturer Part Number: MAX1284
• Description: 400ksps/300ksps / Single-Supply / Low-Power / Serial 12-Bit ADCs with Internal Reference
• Manufacturer: Maxim

Aperture jitter (t
the time between the samples.
Aperture delay (t
falling edge of CS and the instant when an actual sample
is taken.
For a waveform perfectly reconstructed from digital sam-
ples, signal-to-noise ratio (SNR) is the ratio of full-scale
analog input (RMS value) to the RMS quantization error
(residual error). The theoretical minimum analog-to-digital
noise is caused by quantization error, and results directly
from the ADC’s resolution (N bits):
In reality, there are other noise sources besides quantiza-
tion 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 fundamental, the first five
harmonics, and the DC offset.
400ksps/300ksps, Single-Supply, Low-Power,
Serial 12-Bit ADCs with Internal Reference
Figure 14. Power-Supply Grounding Condition
14
*OPTIONAL
V DD
______________________________________________________________________________________
V DD
R* = 10
0.1 F
4.7 F
SNR = (6.02 x N + 1.76)dB
AJ
GND
MAX1284
MAX1285
AD
) is the sample-to-sample variation in
) is the time defined between the
SUPPLIES
Signal-to-Noise Ratio
Aperture Delay
Aperture Jitter
V DD
V DD
CIRCUITRY
DIGITAL
DGND
GND
Signal-to-noise plus distortion (SINAD) is the ratio of the
fundamental input frequency’s RMS amplitude to RMS
equivalent of all other ADC output signals.
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 quantiza-
tion noise only. With an input range equal to the full-scale
range of the ADC, calculate the effective number of bits
as follows:
Total harmonic distortion (THD) is the ratio of the RMS
sum of the first five harmonics of the input signal to the
fundamental itself. This is expressed as:
where V
V
monics.
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.
TRANSISTOR COUNT: 4286
PROCESS: BiCMOS
___________________Chip Information
5
are the amplitudes of the 2nd through 5th-order har-
SINAD (dB) = 20 x log (Signal
THD
1
is the fundamental amplitude, and V
20
ENOB
Signal-to-Noise Plus Distortion
x
Spurious-Free Dynamic Range
log
Total Harmonic Distortion
(
Effective Number of Bits
SINAD
V
6 02
2
.
2
V
3
2
V
1
1 76
RMS
.
V
4
2
)
/Noise
V
5
2
RMS
2
through
)