Datasheet
MAX1421
error specification of less than 1LSB guarantees no
missing codes.
Dynamic Parameter Definitions
Aperture Jitter
Figure 10 depicts the aperture jitter (t
AJ
), which is the
sample-to-sample variation in the aperture delay.
Aperture Delay
Aperture delay (t
AD
) is the time defined between the
falling edge of the sampling clock and the instant when
an actual sample is taken (Figure 10).
Signal-to-Noise Ratio (SNR)
For a waveform perfectly reconstructed from digital
samples, the theoretical maximum SNR is the ratio of
the full-scale analog input (RMS value) to the RMS
quantization error (residual error). The ideal theoretical
minimum analog-to-digital noise is caused by quantiza-
tion error only and results directly from the ADCs reso-
lution (N-bits):
SNR
(MAX)
= (6.02
✕
N + 1.76)dB
In reality, there are other noise sources besides quanti-
zation noise e.g., thermal noise, reference noise, clock
jitter, etc. SNR is computed by taking the ratio of the
RMS signal to the RMS noise, which includes all spec-
tral components minus the fundamental, the first four
harmonics, and the DC offset.
12-Bit, 40Msps, 3.3V, Low-Power ADC
with Internal Reference
14 ______________________________________________________________________________________
INPUT
300Ω
-5V
+5V
0.1µF
0.1µF
0.1µF
0.1µF
C
IN
*
22pF
1nF0.22µF
44pF*
R
ISO
50Ω
R
ISO
50Ω
-5V
600Ω
300Ω
300Ω
INP
INN
LOWPASS FILTER
CML
600Ω
+5V
-5V
0.1µF
300Ω
300Ω
600Ω
300Ω
0.1µF
0.1µF
0.1µF
+5V
0.1µF
300Ω
MAX4108
MAX1421
MAX4108
MAX4108
LOWPASS FILTER
*TWO C
IN
(22pF) CAPS MAY BE REPLACED BY
ONE 44pF CAP, TO IMPROVE PERFORMANCE.
C
IN
*
22pF
Figure 7. Typical Application Circuit for Single-Ended to Differential Conversion