2.5Gbps, +3V to +5.5V, Wide Dynamic Range

Transimpedance Preamplifier

_______________________________________________________________________________________

7

IN

GND

200

Ω

Figure 6. Equivalent Input Circuit

CASE IS GROUND

TOP VIEW OF TO-46 HEADER

PHOTODIODE

MAX3864

OUT+

OUT-

Figure 5. Suggested Layout for TO-46 Header

Photodiode Filter

Supply voltage noise at the photodiode cathode pro-

∆V / ∆t, which reduces the

tance). The filter resistor of the MAX3864, combined

with an external capacitor, can be used to reduce this

noise (see the Typical Application Circuit). Current gen-

erated by supply noise voltage is divided between

ply noise is (assuming the filter capacitor is much larg-

er than the photodiode capacitance):

If the amount of tolerable noise is known, the filter

capacitor can be easily selected:

For example, with a maximum noise voltage equal to

selected to be 250nA (half of the MAX3864’s input noise):

Wire Bonding

For high current density and reliable operation, the

MAX3864 uses gold metalization. Connections to the

die should be made with gold wire only, using ball-

bonding. Wedge bonding is not recommended. Die

thickness is typically 15mils (0.375mm).

C=

100mV

FILTER

()(

)

()(

)

=

085

750

250

453

.pF

nA

pF

Ω

C=

V

FILTER

NOISE

()( )

()(

)

C

RI

PD

FILTER

NOISE

I=

V

NOISE

NOISE

()( )

()(

)

C

RC

PD

FILTER

FILTER