10.7Gbps EAM Driver
Applications Information
Layout Considerations
To minimize loss and crosstalk, keep the connections
between the MAX3935 output and the EAM module as
short as possible. Use good high-frequency layout
techniques and multilayer boards with uninterrupted
ground plane to minimize EMI and crosstalk. Make cir-
cuit boards using low-loss dielectrics. Use controlled-
impedance lines for the clock and data inputs as well
as the modulation output.
Wire Bonding Die
For high-current density and reliable operation, the
MAX3935 uses gold metalization. Make connections to
the die with gold wire only, using ball-bonding tech-
niques. Wedge-bonding processes are not recom-
mended due to possible fracturing of sublayers
caused by stress during bonding. Die thickness is
8 mils (203µm). Die size is 64 mils by 120 mils
(1.626mm by 3.048mm).
The inductance at the high-speed connections for
MOD1, MOD2 and MODN1, MODN2 must be mini-
mized. The minimum length of the bond wires is con-
strained by the type of wire bonder used as well as the
dimensions of the die. Wire length measured in the x-y
plane from the edge of the die should approach 15 mils
if possible. The bond wire must not come closer to the
edge of die than 2X the bond wire diameter. MOD1 and
MOD2 should each have a wire bond to reduce the total
inductance for the MOD output.
Input and Output Schematics
VTT
GND
DATA+
50Ω
50Ω
DATA-
VEE
Figure 4. Equivalent Input Circuit
GND
MODN1 MOD1 MOD2 MODN2
GND
100Ω
150Ω
100Ω
150Ω
150Ω
150Ω
IMOD
VEE
* NOTE: ESD PROTECTION IS INCLUDED ON MOD1, MOD2, MODN1, AND MODN2.
Figure 5. Equivalent Output Circuit
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