Data Sheet
February 1999
LG1605DXB Limiting Amplifier
Features
s
s
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Digital video transmission
Interface between 1319 receiver and LG1600
clock and data regenerator
High-speed comparator
28 dB gain, 34 dB differential
Large dynamic range: >60 dB
Wideband response: 8 kHz to 3 GHz
Extremely low ±4 ps delay skew across input range
Complementary 50
Ω
I/Os
Surface-mount package
Standard ECL supply (400 mW)
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Functional Description
The LG1605DXB is a GaAs wideband limiting ampli-
fier with differential inputs and outputs that provides
28 dB of gain (34 dB differential) and 3 GHz of band-
width in a 50
Ω
environment (Figure 1 shows the
block diagram). At low input levels, below 10 mV to
20 mV, the circuit behaves as a linear amplifier. At
higher levels, the device goes smoothly into limiting.
The device matches the performance of an AGC
amplifier but shows none of the AGC bouncing and
attack characteristics.
V
SS
7
GND
1, 4, 5, 6, 15, 16
Applications
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Data/clock main amplifier SONET/SDH OC-48/
STM-16 transmission systems, DWDM systems
V
BR
8
110 pF
110 pF
V
–REF
V
–IN
V
+IN
V
+REF
110 pF
–
9
10
11
12
50
Ω
25 kΩ
+
50
Ω
+ –
– +
+ –
– +
25 kΩ
CHIP BOUNDARY
3
2
V
–OUT
V
+OUT
13
V
BF
14
V
BS
12-3214(F).r3
Figure 1. LG1605DXB Block Diagram
LG1605DXB Limiting Amplifier
Data Sheet
February 1999
ability to absorb reflections returning from the receiving
end is essential for preventing intersymbol interference
in fiber-optic systems.
The amplifier is a natural step-up interface between
receivers, such as the Lucent Technologies Micro-
eletronics Group Optoelectronics unit 1319 and regen-
erators like the Lucent Technologies Microelectronics
Group LG1600. The referred wideband input noise
(168 µVrms typical) allows for a <1e–9 bit error rate
(BER) for inputs down to 2 mVp-p (S/N ratio of
21.5 dB).
In SAW based clock recovery systems, with clock fre-
quencies as high as 2.5 GHz, the device can provide a
clock-limiting function in systems.
The LG1605DXB is available in a hermetically sealed,
16-lead, glass-metal surface-mount package and uses
a standard ECL supply.
Functional Description
(continued)
The amplifier has a virtually constant output delay for
input signal levels, varying across three decades. As a
result, the device has very low amplitude-to-phase con-
version, which makes it ultimately suitable for applica-
tions in highly sensitive fiber-optic systems. Although
the amplifier is most sensitive when the input is ac cou-
pled (see Figure 3), a low offset (<25 mV) and a large
common-mode input range of 2 V make it useful in
applications that require a high-speed comparator as
well.
A unique input coupling arrangement allows for a fre-
quency response down into the low kHz range while
using coupling capacitors that are small enough to
maintain a good input return loss at high frequencies.
The outputs, when ac coupled, provide a good RF ter-
mination up to very high frequencies. The associated
Pin Information
The pinout for the LG1605DXB is shown in Figure 2.
GND GND V
BS
V
BF
16
15
14
13
1
GND
2
V
+OUT
3
V
–OUT
4
GND
12
V
+REF
11
V
+IN
10
V
–IN
9
V
–REF
5
6
7
8
GND GND V
SS
V
BR
12-3223(F)
Figure 2. Pin Diagram
2
Lucent Technologies Inc.
Data Sheet
February 1999
LG1605DXB Limiting Amplifier
Pin Information
(continued)
The pin descriptions for the LG1605DXB are given in Table 1.
Table 1. Pin Descriptions
Pin
2
3
7
8
9
Symbol
V
+OUT
V
–OUT
V
SS
V
BR
V
–REF
Name/Description
Positive Data Output.
Negative Data Output.
dc Supply Voltage.
Bias Reference Voltage.
Connect to nominal –1.5 V stable voltage refer-
ence, bypassed to GND with a capacitor
≥0.047
µF.
Data Negative Reference.
Internally bypassed with 110 pF. Broadband
operation requires up-close external bypassing with a capacitor
≥0.047
µF,
matching the input coupling capacitor.
Negative Data Input.
Requires ac-coupling capacitor and 50
Ω
source or
termination.
Positive Data Input.
Data Positive Reference.
See pin 9 above.
Bias Force Voltage.
Obsolete function, do not connect.
Bias Sense Voltage.
Internal test point, tracking V
BR
. Normally not con-
nected.
Ground.
For optimum performance, package back should contact board
ground plane. (See the Mounting and Connections section.)
10
11
12
13
14
1, 4, 5, 6,
15, 16,
Package
Back
V
–IN
V
+IN
V
+REF
V
BF
V
BS
GND
Lucent Technologies Inc.
3
LG1605DXB Limiting Amplifier
Data Sheet
February 1999
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 2. Absolute Maximum Ratings
Parameter
Supply Voltage Range (V
SS
)
Power Dissipation
Voltage (all pins)
V
+REF
– V
+IN
V
–REF
– V
–IN
Storage Temperature Range
Operating Case Temperature Range
Min
–7
—
V
SS
—
—
–40
0
Max
0.5
1
0.5
±2
±2
125
100
Unit
V
W
V
V
V
°C
°C
Recommended Operating Conditions
Table 3. Recommended Operating Conditions
Parameter
Case Temperature
Power Supply
Symbol
t
CASE
V
SS
Min
0
–5.7
Max
70
–4.7
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 employs a human-body model (HBM)
and a charged-device model (CDM) for ESD-susceptibility testing and protection 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 4. ESD Threshold
HBM ESD Threshold
Device
LG1605DXB
Voltage
≥200
V
Mounting and Connections
Certain precautions must be taken when using solder. For installation using a constant temperature solder, temper-
atures of under 300 °C may be employed for periods of time up to 5 s, maximum. For installation with a soldering
iron (battery operated or nonswitching only), the soldering tip temperature should not be greater than 300 °C and
the soldering time for each lead must not exceed 5 s. This device is supplied with solder on the back of the pack-
age. Due to the high gain of the device, it is recommended to solder the back of the package to ground.
4
Lucent Technologies Inc.
Data Sheet
February 1999
LG1605DXB Limiting Amplifier
Mounting and Connections
(continued)
Lucent Technologies/FORCE ICs assembly procedure recommendations for the LG1605DXB are as follows:
s
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Board solder pattern for the 1605DXB package base should not exceed 50% of the package base area.
Back lighting can be used during the pick and place operation to silhouette the package in order to eliminate
reflection problems with the solder on the bottom.
Set the lead spacing tolerance to ±0.012 in.
Insertion pressure should not exceed 125 g.
s
s
Electrical Characteristics
t
CASE
= 0 °C to 70 °C, V
BR
= –1.5 V, V
SS
= –4.7 V to –5.7 V, bit rate = 2.488 Mbits/s NRZ, and data pattern =
2
23
– 1 PRBS, unless otherwise indicated.
Note:
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 testing requirements.
Parameter
Data Input Voltage
2
Data Input Voltage
2
Input Offset Voltage
Common-mode Input
Voltage Range
Output Voltage
Output Pulse Width
Relative to Bit Period
Small-signal Output
Transition Time
Small-signal Gain
Small-signal –3 dB
Bandwidth
Low-frequency –3 dB
Cut-off
2
Supply Current
Noise Figure
2
Input Referred Wideband
Noise
Thermal Resistance
Symbol
V
±IN
V
+IN
– V
–IN
V
+REF
– V
–REF
V
CMIN
V
±OUT
PW%
tr, tf
G
f
3dB
f
LF
I
SS
NF
V
nr
θ
JC
Conditions
1
Single-ended source
Differential source
40 °C/–5.2 V; 70 °C/–5.7 V
25 °C, V
SS
= –5.2 V,
dc input coupling
—
Measured on V
+OUT
,
@ 40 °C and 70 °C
25 °C, 20% to 80%,
V
IN
= 8 mVp-p
40 °C to 70 °C, V
IN
=
8 mVp-p
25 °C, V
IN
= 8 mVp-p
V
IN
= 8 mVp-p, input coupling
and bypassing as in Figure 3
—
25 °C, single-ended input
25 °C, single-ended input,
7 kHz—18 GHz
Junction to case
Min
—
—
—
—
400
90
—
26
—
—
—
—
—
—
Typ
—
—
—
–2 to –4
550
100
100
28
3
2.5
85
15
168
30
Max
800
1600
25
—
—
110
—
35
—
8
100
16
—
—
Unit
mVp-p
mVp-p
mV
V
mVp-p
%
ps
dB
GHz
kHz
mA
dB
µVrms
°C/W
1. All temperatures are case temperature, t
CASE
.
2. Parameter guaranteed by design or characterization and not production tested.
Lucent Technologies Inc.
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