MAX1213_09 Datasheet, PDF (15/19 Pages) Maxim Integrated Products – 1.8V, 12-Bit, 170Msps ADC for Broadband Applications

1.8V, 12-Bit, 170Msps ADC for
Broadband Applications
To further enhance THD and SFDR performance at
high-input frequencies (>100MHz), a second trans-
former (Figure 8) should be placed in series with the
single-ended-to-differential conversion transformer.
This transformer reduces the increase of even-order
harmonics at high frequencies.
Single-Ended, AC-Coupled Analog Inputs
Although not recommended, the MAX1213 can be used
in single-ended mode (Figure 9). Analog signals can be
AC-coupled to the positive input INP through a 0.1μF
capacitor and terminated with a 49.9Ω resistor to AGND.
The negative input should be reverse terminated with
49.9Ω resistors and AC-grounded with a 0.1μF capacitor.
Grounding, Bypassing, and
Board Layout Considerations
The MAX1213 requires board layout design techniques
suitable for high-speed data converters. This ADC pro-
vides separate analog and digital power supplies. The
analog and digital supply voltage pins accept input
voltage ranges of 1.7V to 1.9V. Although both supply
types can be combined and supplied from one source,
it is recommended to use separate sources to cut down
on performance degradation caused by digital switch-
ing currents, which can couple into the analog supply
network. Isolate analog and digital supplies (AV_CC and
OV_CC) where they enter the PC board with separate
networks of ferrite beads and capacitors to their corre-
sponding grounds (AGND, OGND).
SINGLE-ENDED
INPUT TERMINAL 0.1μF
ADT1-1WT
ADT1-1WT
25Ω
25Ω
0.1μF
10Ω _INP
INN
10Ω
AV_CC OV_CC
MAX1213
D0P/N–D11P/N
12
AGND OGND
Figure 8. Analog Input Configuration with Back-to-Back Transformers and Secondary-Side Termination
SINGLE-ENDED
INPUT TERMINAL
0.1μF
INP
49.9Ω
1%
0.1μF
INN
49.9Ω
1%
Figure 9. Single-Ended AC-Coupled Analog Input Configuration
AV_CC OV_CC
MAX1213
D0P/N–D11P/N
12
AGND OGND
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