Preliminary Data Sheet
January 1998
LG1628AXA SONET/SDH 2.488 Gbits/s
Transimpedance Amplifier
Features
s
s
s
s
s
s
High data rate: 2.5 Gbits/s
High gain: 5.8 k
Ω
transimpedance
Complementary 50
Ω
outputs
Low noise
Ultrawide dynamic range
Single –5.2 V ECL power supply
A complete receiver/regenerator can be constructed
with an LG1628AXA followed by an LG1605 limiting
amplifier and LG1600 clock and data regenerator.
Figure 1 shows the block diagram of the LG1628AXA
transimpedance amplifier. The amplifier consists of a
4.2 k
Ω
differential transimpedance stage followed by
a limiting buffer that provides complementary 50
Ω
outputs.
R
F
GND
Applications
IN–
s
s
s
OUT+
Z
EFF
OUT–
50
Ω
LIMITING
BUFFER
R
F
V
SS
SONET/SDH receivers
SONET/SDH test equipment
Digital video transmission
IN+
Functional Description
The Lucent Technologies Microelectronics Group
LG1628AXA is a hybrid integrated circuit that com-
bines the Lucent LG1628A gallium arsenide (GaAs)
transimpedance amplifier chip with an external Si
dual operational amplifier and necessary filtering to
achieve an ultrawide dynamic range amplifier. The
LG1628AXA is capable of handling input currents
from 3
µ
A
avg
to 4 mA
avg
(patent pending). Amplifier
operation is from a single –5.2 V power supply. The
targeted transmission system is SONET OC-48 and
SDH STM-16.
OVERLOAD CONTROL
5-5329(F)
Figure 1. LG1628AXA Functional Diagram
LG1628AXA SONET/SDH 2.488 Gbits/s
Transimpedance Amplifier
Preliminary Data Sheet
January 1998
Die Pad Configuration
The die pad configuration is shown in Figure 2.
GND
1
DNC
DNC
GND
2
19
19
18
18
DNC
GND
1
22
21
20
19
19
17
16
15
BG
GND
2
23
24
IN–
24
OUTSIDE DIE DIMENSIONS:
1.62 mm
2
x 1.62 mm
2
PAD SIZE:
100
µm
2
x 100
µm
2
(EXCEPT PAD #23, 100
µm
2
x 150
µm
2
)
PAD SEPARATION:
50
µm
OUT+
15
14
OUT–
14
13
12
V
SS2
12
4
5
6
7
8
9
10
11
V
SS1
11
GND
2
IN+
GND
1
1
2
3
BYPASS
3
OP2
OUT
OP1
OUT
OP1–
OP1+
OP2–
OP2+A
OP2+B
5-5336(F)r.2
Figure 2. Die Pad Configuration
2
Lucent Technologies Inc.
Preliminary Data Sheet
January 1998
LG1628AXA SONET/SDH 2.488 Gbits/s
Transimpedance Amplifier
Die Pad Configuration
(continued)
The pad descriptions for the LG1628AXA are given in Table 1.
Table 1. Pad Descriptions
Pad
1
2, 19, 23
3
4
5
6
7
8
9
10
Symbol
IN+
GND
1
BYPASS
OP2
OUT
OP1
OUT
OP1–
OP1+
OP2–
OP2+A
OP2+B
Description
Amplifier input; connect to detector anode, current should enter this node.
Ground.
Connections between these nodes and an external dual op amp form the over-
load control circuitry. See the test circuit in Figure 4 for wiring details.
To operate the amplifier without overload control connect OP2
OUT
to V
SS
,
OP1
OUT
to GND, and leave BYPASS and the remaining op amp connections
open (Figure 5).
11
12
13, 16, 18
14
15
17
20, 21, 22
24
V
SS1
V
SS2
GND
2
OUT–
OUT+
BG
DNC
IN–
Supply voltage; –5.2 Vdc nominal.
Supply voltage; –5.2 Vdc nominal.
Ground.
Inverted data output (produces low-level output for current entering IN+).
Noninverted data output (produces high-level output for current entering IN+).
Connection for external –2.5 Vdc voltage reference (typically use an Si band-
gap).
Do not connect; internal test point or reserved for future use.
Inverting input; must provide ac bypass to ground when using overload control.
Lucent Technologies Inc.
3
LG1628AXA SONET/SDH 2.488 Gbits/s
Transimpedance Amplifier
Preliminary Data Sheet
January 1998
Typical Connections and Padout of the Hybrid Integrated Circuit
OUT+*
50
Ω
OUT–*
50
Ω
60x30
60x30
60x30 7
5
9
10
4
17
IN+
16
18
2
19
15
60X30
APD
13
8
60x30
60X30
6
60X30
12
APD+
14
3
120X100
20
+V
DET
V
SS
GND THERMISTOR
5-5336(F).r3
* OUT– is delayed approximately 25 ps with respect to OUT+ due to the longer microstrip line associated with OUT–. An extra delay should be
added to OUT+ before connecting to the next circuit.
Figure 3. Typical Connections to the HIC (See Figure 4 for a Schematic of the Circuitry on the HIC.)
Table 2. HIC Pad Functional Description
Symbol
IN+
APD+
+V
DET
V
SS
GND
Thermistor
OUT+
OUT–
Description
Amplifier input; connect to detector anode, current should enter this node.
RF bypassed connection for the cathode of the APD.
APD power supply connection.
Supply voltage; –5.2 Vdc nominal.
Ground (back of HIC is also ground).
Negative temperature coefficient thermistor for APD gain control.
Noninverted data output (produces high-level output for current entering IN+).
Inverted data output (produces low-level output for current entering IN+).
125x60
4
Lucent Technologies Inc.
Preliminary Data Sheet
January 1998
LG1628AXA SONET/SDH 2.488 Gbits/s
Transimpedance Amplifier
Absolute Maximum Ratings
Stresses in excess of the absolute maximum ratings can cause permanent or latent damage to the device. These
are absolute stress ratings only. Functional operation of the device is not implied at these or any other conditions in
excess of those given in the operational sections of the data sheet. Exposure to absolute maximum ratings for
extended periods can adversely affect device reliability.
Table 3. Absolute Maximum Ratings
Parameter
Supply Voltage Range (V
SS
)
Power Dissipation
Voltage (all pins)
Storage Temperature Range
Operating Temperature Range
Min
–7
—
0.5
–40
0
Max
0.5
1
V
SS
125
100
Unit
V
W
V
°
C
°
C
Recommended Operating Conditions
Table 4. Recommended Operating Conditions
Parameter
Ambient Temperature
Power Supply
Symbol
T
A
V
SS
Min
0
–4.7
Max
85
–5.7
Unit
°
C
V
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 Technologies Microelectronics Group
employs a human-body model (HBM) and a charged-device model (CDM) for ESD-susceptibility testing and pro-
tection design evaluation. 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 comparison purposes.
The HBM ESD threshold presented here was obtained by using these circuit parameters.
Table 5. ESD Threshold
HBM ESD Threshold
Device
Voltage
LG1628AXA
>500 V
Lucent Technologies Inc.
5
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