Single +5V, Fully Integrated,

155Mbps Laser Diode Driver

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5

_______________Detailed Description

The MAX3263 laser driver has three main sections: a

reference generator with temperature compensation, a

laser bias block with automatic power control, and a

modulation driver (Figure 1).

The reference generator provides temperature-com-

pensated biasing and a voltage-reference output. The

voltage reference is used to program the current levels

of the high-speed modulation driver, laser diode, and

PIN (p+, intrinsic, n-) monitor diode.

The laser bias block sets the bias current in the laser

diode and maintains it above the threshold current. A

current-controlled current source (current mirror) pro-

grams the bias, with IBIASSET as the input. The mirror’s

gain is approximately 40 over the MAX3263’s input

range. Keep the output voltage of the bias stage above

2.2V to prevent saturation.

The modulation driver consists of a high-speed input

buffer and a common-emitter differential output stage.

The modulation current mirror sets the laser modulation

current in the output stage. This current is switched

between the OUT+ and OUT- ports of the laser driver.

The modulation current mirror has a gain of approximately

20. Keep the voltages at OUT+ and OUT- above 2.2V to

prevent saturation.

MAX3263

VCCB

IPIN

IPINSET

VIN+

VIN-

ENB+

GNDA

ENB-

SLWSTRT

LASER

PHOTO-

DIODE

LOOP-

STABILITY

CAPACITOR

0.1

µF

GNDB

VCCA

OUT+

OUT-

FAILOUT

+2.6V

COMPARATOR

TRANSCONDUCTANCE

AMPLIFIER

MAIN

BIAS

GENERATOR

BANDGAP

REFERENCE

BIAS

COMPEN-

SATION

Figure 1. Functional Diagram