MAX3940 Datasheet, PDF (1/13 Pages) Maxim Integrated Products – 10Gbps EAM Driver with Integrated Bias Network

19-2730; Rev 0; 1/03
10Gbps EAM Driver with Integrated
Bias Network
General Description
The MAX3940 is designed to drive an electro-absorp-
tion modulator (EAM) at data rates up to 10.7Gbps. It
incorporates the functions of a biasing circuit and a
modulation circuit, with integrated control op amps
externally programmed by DC voltages.
The integrated bias circuit provides a programmable
biasing current up to 50mA. This bias current reflects a
bias voltage of up to 1.25V on an external 50Ω load. The
bias and modulation circuits are internally connected on
chip, eliminating the need for an external bias inductor.
A high-bandwidth, fully differential signal path is internally
implemented to minimize jitter accumulation. When a
clock signal is available, the integrated data-retiming
function can be selected to reject input-signal jitter.
The MAX3940 receives differential CML signals (ground
referenced) with on-chip line terminations of 50Ω. The
output has a 50Ω resistor for back termination and is
able to deliver a modulation current of 40mA_P-P to
120mA_P-P, with an edge speed of 23ps (typical, 20% to
80%). This modulation current reflects an EAM modula-
tion voltage of 1.0V_P-P to 3.0V_P-P.
The MAX3940 also includes an adjustable pulse-width
control circuit to precompensate for asymmetrical EAM
characteristics.
Features
o On-Chip Bias Network
o 23ps Edge Speed
o Programmable Modulation Voltage Up to 3V_P-P
o Programmable EAM Biasing Voltage Up to 1.25V
o Selectable Data-Retiming Latch
o Up to 10.7Gbps Operation
o Integrated Modulation and Biasing Functions
o 50Ω On-Chip Input and Output Terminations
o Pulse-Width Adjustment
o Enable and Polarity Controls
o ESD Protection
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX3940E/D
-40°C to +85°C
Dice*
*Dice are designed to operate over a -40°C to +120°C junction
temperature (T_J) range, but are tested and guaranteed at
T_A = +25°C only.
Applications
SONET OC-192 and SDH STM-64 Transmission
Systems
DWDM Systems
Long/Short-Reach Optical Transmitters
10Gbps Ethernet
Typical Application Circuit
-5.2V
DATA+
MAX3952 _DATA-
10Gbps
SERIALIZER
CLK+
CLK-
0.01µF
0.01µF
0.01µF
0.01µF
PLRT MODEN RTEN
GND
50Ω
DATA+
EAM
50Ω
DATA-
MAX3940
50Ω
CLK+
OUT
50Ω
-5.2V
CLK-
PWC+
PWC-
2kΩ
MODSET BIASSET
+
VMODSET
-
+
VBIASSET
-
VEE
-5.2V
REPRESENTS A CONTROLLED-IMPEDANCE TRANSMISSION LINE.
50Ω
-5.2V
330pF
0.1µF
________________________________________________________________ Maxim Integrated Products 1
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