MAX107 Maxim, MAX107 Datasheet - Page 16

• Manufacturer Part Number: MAX107
• Description: Dual / 6-Bit / 400Msps ADC with On-Chip / Wideband Input Amplifier
• Manufacturer: Maxim

Grounding and power supply decoupling strongly influ-
ence the MAX107’s performance. At 400MHz clock fre-
quency and 6-bit resolution, unwanted digital crosstalk
may couple through the input, reference, power supply,
ground connections, and adversely influence the
dynamic performance of the ADC. In addition, the I&Q
inputs may crosstalk through poorly designed decou-
pling circuits. Therefore, closely follow the grounding
and power-supply decoupling guidelines in
Maxim strongly recommends using a multilayer printed
circuit board (PC board) with separate ground and
power supply planes. Since the MAX107 has separate
analog and digital ground connections (AGND, AGNDI,
AGNDQ, AGNDR, OGNDI, and OGNDQ, respectively).
The PC board should feature separate sections desig-
nated to analog (AGND) and digital (OGND), connect-
ed at only one point. Digital signals should run above
the digital ground plane and analog signals should run
above the analog ground plane. Keep digital signals far
away from the sensitive analog inputs, reference inputs,
and clock inputs. High-speed signals, including clocks,
Dual, 6-Bit, 400Msps ADC with On-Chip,
Wideband Input Amplifier
Figure 8. Typical I/Q Application
16
FROM PREVIOUS STAGE
DEMODULATOR
______________________________________________________________________________________
QUADRATURE
MAX2108
90°
NYQUIST
NYQUIST
FILTER
FILTER
LO
Grounding, Bypassing,
2kΩ
2kΩ
and Board Layout
PRE-AMP
PRE-AMP
CM BUFFER
CM BUFFER
Figure 9.
REFERENCE
REF
REF
Q ADC
I ADC
analog inputs, and digital outputs, should be routed on
50Ω microstrip lines, such as those employed on the
MAX105EV kit.
The MAX107 has separate analog and digital power-
supply inputs:
•
•
•
•
•
•
All supplies should be decoupled with large tantalum or
electrolytic capacitors at the point they enter the PC
board. For best performance, bypass all power sup-
plies to the appropriate ground with a 10µF tantalum
AV
input section of the clock circuit.
AV
common-mode buffer, pre-amp and quantizer.
AV
nel common-mode buffer, pre-amp and quantizer.
AV
bandgap reference.
OV
nel output drivers and DREADY circuitry.
OV
Q-channel output drivers and DOR circuitry.
DOR
CC
CC
CC
CC
CC
CC
1:2
I = +5V ±5%: Power supply for the I-channel
Q = +5V ±5%: Power supply for the Q-chan-
R = +5V ±5%: Power supply for the on-chip
I = +3.3V ±10%: Power supply for the I-chan-
Q = +3.3V ±10%: Power supply for the
= +5V ±5%: Power supply for the analog
DATA PORT
DATA PORT
DATA PORT
DATA PORT
AUXILIARY
AUXILIARY
PRIMARY
PRIMARY
P0Q-P5Q
A0Q-A5Q
P0I-P5I
A0I-A5I
DREADY+/DREADY-
DOR+/DOR-
AV
CC
10kΩ
10kΩ
D
S
P