Data Sheet
February 1999
LG1626DXC Modulator Driver
Features
■High data-rate optical modulator driver
■Adjustable output voltage up to 3 Vp-p (RL = 50 Ω)
■Adjustable modulator dc offset
■Operation up to 3 Gbits/s
■Single ended or differential inputs
■Single –5.2 V power supply
■90 ps rise and fall times
■Enable control
Applications
■SONET/SDM transmission systems
■SONET/SDM test equipment
■Optical transmitters
Functional Description
The LG1626DXC is a gallium-arsenide (GaAs) inter-
grated circuit used to provide voltages to driv e optical
modulators in high-speed non-return-to-zero (NRZ)
transmission systems. The device is made in a high-
performance 0.9 µm gate GaAs hetero-junction FET
technolog y that utilizes high-density MIM capacitors,
airbr id ge int er co nnec t, and NiCr film precis i on resi s-
tors. The device contains four cascaded stages,
operates with a single –5.2 V power supply, and
accepts ECL 100K level inputs. The output is an
open drain designed to drive 50 Ω loa ds. Volta ges
control the output modulation amplitude and modula-
tor dc offset. A –2.5 V band-gap ref erence is required
for stable operation over temperature and varying
power supply voltage. The LG1626DXC is available
in a 24-lead hermetic, gull-wing package.
5-6549(F)
Figure 1. Functional Diagram
VIN
BG2P5
VSS1
VTH
VSS2
GND
VOUT
MK MK
VSS3
VMOD
VOUT-DC
MOD_E
VIN
VTH
VDC-ADJ
2Lucent Technologies Inc.
Data Sheet
February 1999
LG1626DXC Modulator Driver
Pin Information
5-6550(F)
Figure 2. LG1626DXC Die Block Diagram
VTH
VIN
VOUT
VSS3
VMOD
VSS1
50 Ω
GND MKMK
VSS2
VDC-ADJ
50 Ω
+
–
+
–
VIN
VTH
50 Ω
MOD_E
Lucent Technologies Inc. 3
Data Sheet
February 1999 LG1626DXC Modulator Driver
Pin Information (continued)
5-6551(F)
Note: Figure is not to scale.
Figure 3. LG1626DXC Package Pinout
Table 1. LG1626DXC Pin Description
*
National
Semiconductor
is a registered trademark of National Semiconductor Corporation.
Symbol Pin Description
GND 1, 3, 4, 9, 10, 13, 14, 15,
Pac kage Bottom Ground. F or optimum performance, the package bottom must be
soldered to the ground plane.
VIN 2 Data input.
5 Complementary data input.
6 Complementary threshold control (eye crossing) input.
BG2P5 7 –2.5 V band-gap reference (
National
Semiconductor
* LM4040).
MOD_E 8 Modulation enable (connect to VSS1 to enable, float to disable).
MK 11 Complementary mark density output.
MK 12 Mark density output.
VOUT 16 Output, ac couple to 50 Ω modulator.
VOUT-DC 17 Output, modulator dc offset.
VDC-ADJ 18 Modulator dc offset control input.
VSS2 19 VSS2 supply –5.2 V for output prebias.
VSS3 20 VSS3 supply –5.2 V for output modula tion.
VMOD 21 Output modulation control input.
VSS1 22, 23 VSS1 supply –5.2 V.
VTH 24 Threshold control (eye crossing) input.
GND
GND
GND
V
OUT
V
OUT-DC
V
DC-ADJ
V
SS2
VSS3
V
MOD
V
SS1
V
SS1
V
TH
1
2
3
4
5
613
14
15
16
17
18
24
BG2P5
MOD_E
GND
GND
MK
MK
GND
V
IN
GND
GND
V
IN
V
TH
23
22
21
20
19
7
8
9
10
11
12
LG1626DXC
MODULATOR
DRIVER
VIN
----------
VTH
-----------
4Lucent Technologies Inc.
Data Sheet
February 1999
LG1626DXC Modulator Driver
Absolute Maximum Ratings (at TA = 25 °C unless otherwise specified)
Table 2. Absolute Maximum Ratings
Handling Precautions
Although protection circuitry has been designed into this device, proper precautions should be taken to avoid expo-
sure to electrostatic discharge (ESD) during handling and mounting. Lucent employs a human-body model (HBM)
and a charged-device model (CDM) for ESD-susceptibility testing and protection design evaluation. ESD voltage
threshold are dependent on the circuit parameters used to define the model. No industry-wide standard has been
adopted for the CDM. However, a standard HBM (resistance = 1500 Ω, capacitance = 100 pF) is widely used and
therefore, can be used for comparision. The HBM ESD threshold presented here was obtained by using these cir-
cuit parameter s.
Table 3. ESD Threshold Voltage
Mounting and Connections
Cetain precautions must be taken when using solder. For installation using a constant temperature solder, temper-
atures of under 300 °C ma y be employed for periods of time up to 5 seconds, maximum. For installation with a sol-
dering iron (battery operated or nonswitching only), the soldering tip temperature should not be greater than
300 °C and the soldering time f or each lead must not e xceed 5 seconds. This device is supplied with solder on the
back of the package. For optimum performance, it is recommended to solder the back of the package to the
ground.
Parameter Symbol Min Max Unit
Supply Voltage VSS —5.75V
Input Voltage VIGND VSS V
Power Dissipation PD—1W
Storage Temperature Range Tstg –40 125 °C
Operating Temperature Range TC0 100 °C
Human-Body Model ESD Threshold
Device Voltage
LG1626DXC >200 V
Lucent Technologies Inc. 5
Data Sheet
February 1999 LG1626DXC Modulator Driver
Electrical Characteristics
TA = 25 °C, VSS1 = VSS2 = VSS3 = –5.2 V, VTH = – 1.3 V, VMOD = – 3.8 V, RL = 50 Ω.
Minimum and maximum values are testing requirements. Typical values are characteristics of the device and are
the result of engineering evaluations. Typical values are for information purposes only and are not part of the test-
ing requirements. Stresses in excess of the absolute maximum ratings can cause permanent damage to the
device.
Table 4. LG1626DXC Minimum and Maximum Values
1. Maximum output modulation at maximum VMOD (RL = 50 Ω).
2. Minimum output modulation when MOD_E is floating and VMOD = VSS3.
3. Excludes IPRE and average IMOD:
Power suppy current ISS2 (relating to prebias) is dependent on VPRE.
Power suppy current ISS3 (relating to modulation) is dependent on VMOD.
4. Both MK and MK are open drains, the typical value is obtained by driving a 1kΩ load.
5. Maximum modulator dc offset voltage (RL = 50 Ω) at maximum VDC-ADJ.
6. Minimum modulator dc offset voltage (RL = 50 Ω) at VDC-ADJ = VSS2.
Note: All parameters measured at 25 °C ambient.
Parameter Symbol Min Typ Max Unit
Data Input Voltage (peak to peak) Single Ended VIN 300 600 1000 mV
Voltage Control for Output Modulation Current VMOD –5.5 — –4 V
Maximum Modulated Output Voltage1VOUT 2.70 — 3.00 V
Minimum Modu lat ed Out put Vo lta ge2VOUT 0—0.2V
Output Rise and Fall Times (20%—80%) tR, tF—90—ps
Power Supply Voltage VSS1, VSS2, VSS3 –5.5 –5.2 –4.9 V
Power Supply Current3ISS1 100 140 180 mA
Mark Density4MK — –0.5 — V
Complementary Mark Density4MK — –0.5 — V
Voltage Control for Modulator dc Offset VDC-ADJ –5.5 — –3 V
Maximum Output, Modulator dc Offset5VOUT-DC 1.2 — 1.5 V
Minimum Output, Modulator dc Offset6VOUT-DC 0—0.1V
6Lucent Technologies Inc.
Data Sheet
February 1999
LG1626DXC Modulator Driver
Electrical Characteristics (continued)
5-6553(F).b
*A 2.5 kΩ resistor will set the eye crossing at 50%. A 5 kΩ potentiometer will allow the eye crossing to be var ied.
Notes:
All bypass caps should be mounted close to the package.
ISS3 can be measured and used to control VMOD.
ISS2 can be measured and used to control VOUT-DC.
For optimal performance, the proximity of the two components should be minimized and the package bottom must be soldered to the circuit
board (GND).
For proper impedance matching, high-speed transmission lines should be 50 Ω controlled impedance lines.
Figure 4. LG1626DXC Typical Electrical Evaluation (ac Coupled to Scope)
VOLTAGE
DIVIDER
CURRENT
SENSE
V
SS1
BYPASS
1
2
3
4
5
67 8 9 10 11 1213
14
15
16
17
18
192021222324
LG1626DXC
MODULATOR
DRIVER 50
Ω
50
Ω
+
DATA
GENERATOR
SCOPE
Zo = 50
Ω
DATA IN
V
SS1
V
SS3
V
MOD
2.5 k
Ω
*
V
SS
= –5.2 V
0.047
µ
F
1 k
Ω
1 k
Ω
MK MK
1
Ω
3 k
Ω
2 k
Ω
V
SS
0.1
µ
F
REQUIRED TO SET
V
MOD
AND V
DC-ADJ
TO ACHIEVE DESIRED
MODULATION, ONE EACH.
VOLTAGE
DIVIDER
V
SS
0.1
µ
F
TO USER-SUPPLIED
VOLTAGE MONITOR
TO NODE
V
SS2
AND V
SS3
(DVM).
CURRENT
SENSE
ONE EACH.
0.1
µ
F
V
SS
BYPASS
FOR V
SS1
V
SS1
V
TH
V
IN
V
OUT
V
SS2
V
OUT-DC
V
DC-ADJ
VOLTAGE
DIVIDER
CURRENT
SENSE
Zo = 50
Ω
0.1
µ
F
10
Ω
0.1
µ
F
BG2P5
LM4040
MOD_5
V
SS
= –5.2 V
10
Ω
0.047
µ
F
2.5 k
Ω
10
Ω
0.1
µ
F
50
Ω
Lucent Technologies Inc. 7
Data Sheet
February 1999 LG1626DXC Modulator Driver
Electrical Characteristics (continued)
5-6554(F).b
*A 2.5 kΩ resistor will set the eye crossing at 50%. A 5 kΩ potentiometer will allow the eye crossing to be v aried.
Notes:
All bypass caps should be mounted close to the package.
ISS3 can be measured and used to control VMOD.
ISS2 can be measured and used to control VOUT-DC.
For optimal performance, the proximity of the two components should be minimized and the package bottom must be soldered to the circuit
board (GND).
For proper impedance matching, high-speed transmission lines should be 50 Ω controlled impedance lines.
Figure 5. Typical Optical Evaluation of the LG1626DXC and EM2500 EM-ILM
VOLTAGE
DIVIDER
CURRENT
SENSE
VSS1
BYPASS
VSS1
VSS3
VMOD
VTH
VSS2
CURRENT
SENSE
1
2
3
4
5
6
7 8 9 10 11 12 13
14
15
16
17
18
192021222324
LG1626DXC
MODULATOR
DRIVER Zo = 50
Ω
Zo = 50
Ω
DATA
2.5 k
Ω
*
0.1
µ
F
VSS = –5.2 V
0.047
µ
F
1 k
Ω
1 k
Ω
MK MK
VIN
VOUT
VOUT-DC
VDC-ADJ
VOLTAGE
DIVIDER
Zo = 50
Ω
1
2
3
4
5
6
7
14
13
12
11
10
9
8
E2500
EM-ILM
INPUT +2 V
MAX
DMM
dc
SUPPLY
0.1
µ
F
IN
VSS = –5.2 V
MOD_E
BG2P5
LM4040
50
Ω
+
DATA
GENERATOR
0.047
µ
F
2.5 k
Ω
10
Ω
0.1
µ
F
10
Ω
10
Ω
50
Ω
50
Ω
0.047
µ
F
10
µ
H
10
µ
H
100
µ
H
8Lucent Technologies Inc.
Data Sheet
February 1999
LG1626DXC Modulator Driver
Electrical Characteristics (continued)
5-7341(F)
Figure 6. Typical Electrical Eye Diagram (ac Coupled to Scope)
5-7342(F)
Figure 7. Typical Optical Eye Diagram
Table 5. Pin Description of Lucent’s E2500 EM-ILM Modulator
Pin Description
1, 2 Thermistor
3 Laser Anode
4 Monitor Anode
5 Monitor Cathode
6 Thermoelectric Cooler (+)
7 Thermoelectric Cooler (–)
8, 9 Case Ground
10, 14 No Connect
11, 13 Laser/Modulator Ground
12 Modulato r Ano de (–) 50 ΩRF Input
750 mV/div
80 ps/div
500 mW/div
60 ps/div
Lucent Technologies Inc. 9
Data Sheet
February 1999 LG1626DXC Modulator Driver
Outline Diagram
12-3224(F).a
Assembly Notes:
Standoff specifications applies to package prior to solder dipping of leads and package base.
During board assembly use back lighting to silhouette the package. This will eliminate reflection problems with the
solder on the bottom of the package.
Lead space tolerance should be set to ± 0.012 in.
Board solder pattern for the package base should not exceed 50% of the package base area.
Insertion pressure should not exceed 125 grams.
LG1626DXC Ordering Information
Device Type Comcode Number
LG1626 DXC 24-Pin Package 10819286 5
1
1
0 — 0.004
0.082
0.005
0.092 0.045
0.035
0.030
0.012
0.280
0.465
LUCENT
LG1626DXC
XXXXXXX
Lucent Technologies Inc. reserves the right to make changes to the product(s) or information contained herein without notice. No liability is assumed as a result of their use or application. No
rights under any patent accompany the sale of any such product(s) or information.
Copyright © 1999 Lucent Technologies Inc.
All Rights Reserved
February 1999
DS99-145HSPL
For additional information, contact your Microelectronics Group Account Manager or the following:
INTERNET: http://www.lucent.com/micro
E-MAIL: docmaster@micro.lucent.com
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1-800-372-2447, FAX 61 0-712-4106 ( In CANADA: 1-800-553-2448, FAX 610-712-4106)
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Tel. (65) 778 8833, FAX (65) 777 7495
CHIN A: Microelec tr onics G r ou p, Lucen t Technologies ( C hina) Co., Ltd ., A - F2, 23/ F, Zao Fong Univer s e B uildin g, 1800 Zhon g S han Xi Road, Sha nghai
200233 P. R. China Tel. (86) 21 644 0 0468, ext. 316, FAX (86) 21 6440 065 2
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Tel. (81) 3 5421 1600, FAX (81) 3 5421 1700
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Technical Inqui ries:GERMANY: (49) 89 95086 0 (Munich), UNITED KINGDOM: (44) 1344 865 900 (Ascot),
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