10.7Gbps EAM Driver

10

______________________________________________________________________________________

DATA+

DATA-

50

Ω

50

Ω

GND

GND

MODN1 MOD1 MOD2

100

Ω

150

Ω

150

Ω

MODN2

100

Ω

150

Ω

150

Ω

GND

* NOTE: ESD PROTECTION IS INCLUDED ON MOD1, MOD2, MODN1, AND MODN2.

Figure 4. Equivalent Input Circuit

Figure 5. Equivalent Output Circuit

Input and Output Schematics

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.