MAX1421 Maxim, MAX1421 Datasheet - Page 15

• Manufacturer Part Number: MAX1421
• Description: 12-Bit / 40Msps / +3.3V / Low-Power ADC with Internal Reference
• Manufacturer: Maxim

Figure 10. Track-and-Hold Aperture Timing
Figure 8. Using a Transformer for AC-Coupling
Figure 9. Single-Ended AC-Coupled Input Signal
DATA (T/H)
SAMPLED
ANALOG
INPUT
CLK
CLK
T/H
t
AD
TRACK
______________________________________________________________________________________
V
IN
12-Bit, 40Msps, +3.3V, Low-Power ADC
t
HOLD
AJ
MAX4108
V
IN
0.1µF
100Ω
100Ω
N.C.
*REPLACE BOTH 22pF CAPS WITH 44pF BETWEEN
INP AND INN TO IMPROVE DYNAMIC PERFORMANCE.
TRACK
MINICIRCUITS
3
T1–1T–KK81
1
2
T1
0.1µF
6
5
4
0.22µF
25Ω
25Ω
0.22µF
1kΩ
50Ω
R
22pF
22pF
ISO
1nF
with Internal Reference
*
*
44pF
SINAD is computed by taking the ratio of the RMS sig-
nal to all spectral components minus the fundamental
and the DC offset.
ENOB specifies the dynamic performance of an ADC at
a specific input frequency and sampling rate. An ideal
ADC’s error consists of quantization noise only. ENOB
is computed from:
*
1nF
C
22pF
IN
22pF
50Ω
R
C
ISO
IN
INP
CML
INN
MAX1421
ENOB
Signal-to-Noise Plus Distortion (SINAD)
INP
CML
INN
MAX1421
=
Effective Number of Bits (ENOB)
SINADdB
6 02
.
dB
-
1 76
.
dB
15