Rainbow Electronics MAX3941 User Manual
General Description
The MAX3941 is designed to drive an electro-absorption 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 MAX3941 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 (20% to 80%
typ). This modulation current reflects an EAM modulation voltage of 1.0V
P-P
to 3.0V
P-P
.
The MAX3941 also includes an adjustable pulse-width
control circuit to precompensate for asymmetrical EAM
characteristics. It is available in a compact 4mm x
4mm, 24-pin thin QFN package and operates over the
-40°C to +85°C temperature range.
Features
♦ On-Chip Bias Network
♦ 23ps Edge Speed
♦ Programmable Modulation Voltage Up to 3V
P-P
♦ Programmable EAM Biasing Voltage Up to 1.25V
♦ Selectable Data-Retiming Latch
♦ Up to 10.7Gbps Operation
♦ Integrated Modulation and Biasing Functions
♦ 50Ω On-Chip Input and Output Terminations
♦ Pulse-Width Adjustment
♦ Enable and Polarity Controls
♦ ESD Protection
Applications
SONET OC-192 and SDH STM-64
Transmission Systems
DWDM Systems
Long/Short-Reach Optical Transmitters
10Gbps Ethernet
MAX3941
10Gbps EAM Driver with Integrated
Bias Network
________________________________________________________________ Maxim Integrated Products 1
Typical Application Circuit
19-2935; Rev 0; 7/03
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Ordering Information
PART TEMP RANGE PIN-PACKAGE
MAX3941ETG -40°C to +85°C
24-Thin QFN
(4mm x 4mm)
-5.2V
MODEN
0.01µF
DATA+ DATA+
MAX3952
10Gbps
SERIALIZER
REPRESENTS A CONTROLLEDIMPEDANCE TRANSMISSION LINE.
0.01µF
DATA- DATA-
0.01µF
CLK+ CLK+
0.01µF
CLK- CLK-
50Ω
50Ω
50Ω
50Ω
-5.2V
PLRT GND
PWC+ PWC- V
2kΩ
RTEN
MAX3941
MODSET BIASSET
+
V
V
MODSET
BIASSET
-
EAM
OUT
EE
+
-
-5.2V
50Ω
330pF
-5.2V
0.1µF
MAX3941
10Gbps EAM Driver with Integrated
Bias Network
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
Supply Voltage V
EE
..............................................-6.0V to +0.5V
Voltage at MODEN,
RTEN, PLRT, MODSET, BIASSET ...........(V
EE
- 0.5V) to +0.5V
Voltage at DATA+, DATA-, CLK+, and CLK-……-1.65V to +0.5V
Voltage at OUT .............................................……….-4V to +0.5V
Voltage at PWC+, PWC- ...................(V
EE
- 0.5V) to (VEE+ 1.7V)
Current Into or Out of OUT.............................……………...80mA
Continuous Power Dissipation (T
A
= +85°C)
24-Lead Thin QFN
(derate 20.8mW/°C above +85°C).............................1354mW
Storage Temperature Range .....................……-55°C to +150°C
Operating Temperature Range ....................……-40°C to +85°C
Lead Temperature (soldering, 10s) .................................+300°C
ELECTRICAL CHARACTERISTICS
(VEE= -5.5V to -4.9V, TA= -40°C to +85°C. Typical values are at VEE= -5.2V, I
BIAS
= 30mA, I
MOD
= 100mA, and TA= +25°C, unless
otherwise noted.)
Power-Supply Voltage V
Supply Current I
Power-Supply Noise Rejection PSNR f ≤ 2MHz (Note 2) 15 dB
SIGNAL INPUT (Note 3)
Input Data Rates NRZ 10.7 Gbps
Single-Ended Input Resistance R
Single-Ended Input Voltage V
Differential Input Voltage V
Differential Input Return Loss RL
EAM BIAS
Maximum Bias Current V
Minimum Bias Current V
BIASSET Voltage Range V
Equivalent Bias Resistance R
Bias-Current-Setting Accuracy TA = +25°C
Bias-Current Temperature
Stability
BIASSET Input Resistance 20 kΩ
BIASSET Bandwidth
EAM MODULATION
Maximum Modulation Current 112 120 mA
Minimum Modulation Current V
MODSET Voltage Range V
E q ui val ent M od ul ati on Resi stance R
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
EE
EE
BIASSET
BSEQV
Excluding I
(Note 1)
I
MOD
Input to GND 42.5 50 58.5 Ω
IN
DC-coupled, Figure 1a -1 0
IS
AC-coupled, Figure 1b -0.4 +0.4
DC-coupled (Note 4) 0.2 2.0
ID
AC-coupled (Note 4) 0.2 1.6
≤15GHz 15 dB
IN
BIASSET
BIASSET
(Note 5) 36.4 Ω
(Note 6)
50Ω driver load, V
Figure 2
MODSET
MODSET
MODEQV
(Note 7) 11.1 Ω
-5.5 -4.9 V
Retime disabled 124 174
and
BIAS
Retime enabled 140 201
= VEE + 2V 50 56 mA
= V
= V
EE
EE
V
BIASSET
V
BIASSET
V
BIASSET
V
BIASSET
V
BIASSET
BIASSET
V
EE
= VEE + 0.11V 2.1 4.3
= VEE + 0.36V 8.8 11.3
= VEE + 2.0V 52 58.4
< VEE + 0.36V -1100 +1100
≥ VEE + 0.36V -480 +480
= VEE + 0.55V,
V
EE
0.3 1.2 mA
VEE + 2 V
5MHz
37 40 mA
VEE + 1 V
mA
V
V
P-P
mA
ppm/°C
P-P
P-P
MAX3941
10Gbps EAM Driver with Integrated
Bias Network
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (continued)
(VEE= -5.5V to -4.9V, TA= -40°C to +85°C. Typical values are at VEE= -5.2V, I
BIAS
= 30mA, I
MOD
= 100mA, and TA= +25°C, unless
otherwise noted.)
Note 1: Supply current remains elevated once the retiming function is enabled. Power must be cycled to reduce supply
current after the retiming function is disabled.
Note 2: Power-supply noise rejection is specified as PSNR = 20log(V
noise (on Vcc)
/ ∆V
OUT
). V
OUT
is the voltage across a 50Ω load.
V
noise (on Vcc)
= 100mV
P-P
.
Note 3: For DATA+, DATA-, CLK+, and CLK-.
Note 4: CLK input characterized at 10.7Gbps.
Note 5: R
BSEQV
= (V
BIASSET
- VEE) / I
BIAS
with MODEN = VEE, DATA+ = high, and DATA- = low.
Note 6: Guaranteed by design and characterization using the circuit shown in Figure 4.
Note 7: R
MODEQV
= (V
MODSET
- VEE) / (I
MOD
- 37mA) with BIASSET = VEE.
Note 8: 50Ω load, characterized at 10.7Gbps with a 1111 1111 0000 0000 pattern.
Note 9: Deterministic jitter is defined as the arithmetic sum of pulse-width distortion (PWD) and pattern-dependent jitter (PDJ).
Measured with a 10.7Gbps 2
7
- 1 PRBS pattern with eighty 0s and eighty 1s inserted in the data pattern.
Note 10: For MODEN and PLRT.
Modulation Set Bandwidth
MODSET Input Resistance 20 kΩ
Modulation-Current Temperature
Stability
Modulation-Current-Setting Error 50Ω driver load, TA = +25°C -10 +10 %
Output Resistance R
Total Off Current
Output Return Loss RL
Output Edge Speed 20% to 80% (Notes 6, 8) 23 32 ps
Setup/Hold Time tSU, t
Pulse-Width Adjustment Range (Notes 6, 8) ±30 ±50 ps
Pulse-Width Control Input Range
(Single Ended)
Pulse-Width Control Input Range
(Differential)
Output Overshoot δ (Notes 6, 8) 10 %
Driver Random Jitter RJ
Driver Deterministic Jitter DJ
CONTROL INPUTS
Input High Voltage V
Input Low Voltage V
Input Current (Note 10) -80 +200 µA
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Modulation depth 10%, 50Ω driver load,
Figure 2
(Note 6) -957 0 ppm/°C
OUT
OUT to GND 42.5 50 58.5 Ω
BIASSET = V
V
, DATA+ = high, DATA- = low
EE
I
= 30mA,
OUT
DR
DR
IH
IL
BIAS
I
= 50mA
MOD
Figure 3 (Note 6) 25 ps
HD
For PWC+ and PWC-
(PWC+) - (PWC-) -0.5 +0.5 V
(Note 6) 0.3 0.7 ps
PWC- = GND (Notes 6, 9) 6.8 11 ps
(Note 10)
(Note 10)
, MODEN = VEE, MODSET =
EE
≤15GHz 10 dB
5 MHz
1.2 mA
V
+
EE
0.5
V
+
EE
2.0
VEE +
1.5
V
EE
0.8
+
V
RMS
P-P
V
V
MAX3941
10Gbps EAM Driver with Integrated
Bias Network
4 _______________________________________________________________________________________
Figure 1. Definition of Single-Ended Input Voltage Range
Figure 2. Modulating BIASSET and MODSET Pins
Test Circuits and Timing Diagrams
0V
-0.5V
-1.0V
(a) DC-COUPLED SINGLE-ENDED CML INPUT
0.4V
0V
-0.4V
(b) AC-COUPLED SINGLE-ENDED (CML OR PECL) INPUT
0V
100mV
1.0V
800mV
100mV
0V
V
OUT
V
0V
NOTE: ALL AMPLITUDES ARE RELATIVE.
(a) MODULATING BIASSET
(b) MODULATING MODSET
BIASSET
V
OUT
V
MODSET
mW
(c) RESULT OF MODULATING BIASSET
AND MODSET 180° OUT OF PHASE
(d) RESULTING OPTICAL OUTPUT
V
OUT
P
OUT
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