19-2717; Rev 6; 6/11
KIT
ATION
EVALU
BLE
AVAILA
Compact 155Mbps to 4.25Gbps
Limiting Amplifier
General Description
Features
♦
SFP Reference Design Available
♦
16-Pin TQFN Package with 3mm x 3mm Footprint
♦
Single 3.3V Supply Voltage
♦
86ps Rise and Fall Time
♦
Loss of Signal with Programmable Threshold
♦
RSSI Interface (with MAX3744 TIA)
♦
Output Disable
♦
Polarity Select
♦
8.7ps
P-P
Deterministic Jitter (4.25Gbps)
MAX3748
The MAX3748 multirate limiting amplifier functions as a
data quantizer for SONET, Fibre Channel, and Gigabit
Ethernet optical receivers. The amplifier accepts a wide
range of input voltages and provides constant-level
current-mode logic (CML) output voltages with con-
trolled edge speeds.
A received-signal-strength indicator (RSSI) is available
when the MAX3748 is combined with the MAX3744 SFP
transimpedance amplifier (TIA). A receiver consisting of
the MAX3744 and the MAX3748 can provide up to
19dB RSSI dynamic range. Additional features include
a programmable loss-of-signal (LOS) detect, an option-
al disable function (DISABLE), and an output signal
polarity reversal (OUTPOL). Output disable can be
used to implement squelch.
The combination of the MAX3748 and the MAX3744
allows for the implementation of all the small-form-factor
SFF-8472 digital diagnostic specifications using a stan-
dard 4-pin TO-46 header. The MAX3748 is packaged in
a 3mm x 3mm, 16-pin thin QFN package with an
exposed pad.
Ordering Information
PART
MAX3748HETE#G16*
MAX3748ETE
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
16 TQFN-EP**
16 TQFN-EP**
Applications
Gigabit Ethernet SFF/SFP Transceiver Modules
Fibre Channel SFF/SFP Transceiver Modules
Multirate OC-3 to OC-48-FEC SFF/SFP
Transceiver Modules
H = hybrid lead-free package. *See Detailed Description for
more information. The MAX3748H is the MAX3748 in a hybrid
lead-free package.
#Denotes a RoHS-compliant device that may include lead that
is exempt under the RoHS requirements.
**EP
= Exposed pad.
Functional Diagram and Pin Configuration appear at end of
data sheet.
Typical Operating Circuits
SFP OPTICAL RECEIVER
4-PIN TO HEADER
0.1μF
OUTPOL
IN+
MAX3744 TIA
HOST BOARD
SUPPLY FILTER
HOST FILTER
V
CC
_RX
V
CC
CAZ1
CAZ2
OUT+
0.1μF
50Ω
0.1μF
SERDES
50Ω
IN-
OUT-
MAX3748
RSSI
DS1858
3-INPUT DIAGNOSTIC
MONITOR
R1
3kΩ
C1
0.1μF
TH
R
TH
GND
DISABLE
LOS
4.7kΩ TO 10kΩ
V
CC
_HOST
LOS
Typical Operating Circuits continued at end of data sheet.
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
Compact 155Mbps to 4.25Gbps
Limiting Amplifier
MAX3748
ABSOLUTE MAXIMUM RATINGS
Power-Supply Voltage (V
CC
) .................................-0.5V to +6.0V
Voltage at IN+, IN- ..........................(V
CC
- 2.4V) to (V
CC
+ 0.5V)
Voltage at DISABLE, OUTPOL, RSSI,
CAZ1, CAZ2, LOS, TH............................-0.5V to (V
CC
+ 0.5V)
Current into LOS ...................................................-1mA to +9mA
Differential Input Voltage (IN+ - IN-) .....................................2.5V
Continuous Current at CML Outputs
(OUT+, OUT-) ...............................................-25mA to +25mA
Continuous Power Dissipation (T
A
= +70°C)
TQFN (derate 17.7mW above +70°C)..............................1.4W
Operating Junction Temperature Range (T
J
) ....-55°C to +150°C
Storage Ambient Temperature Range (T
s
)........-55°C to +150°C
Lead Temperature (soldering, 10s) .................................+260°C
Soldering Temperature (reflow)
TQFN............................................................................+240°C
Hybrid TQFN ................................................................+250°C
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.
ELECTRICAL CHARACTERISTICS
(V
CC
= 2.97V to 3.63V, ambient temperature = -40°C to +85°C, CML output load is 50Ω to V
CC
, C
AZ
= 0.1µF, typical values are at
+25°C, V
CC
= 3.3V, unless otherwise specified. The data input transition time is controlled by a 4th-order Bessel filter with f
-3dB
=
0.75
✕
2.667GHz for all data rates of 2.667Gbps and below, and with f
-3dB
= 0.75
✕
data rate for data rates > 3.2Gbps.)
PARAMETER
Single-Ended Input Resistance
Input Return Loss
Input Sensitivity
Input Overload
Single-Ended Output Resistance
Output Return Loss
Differential Output Voltage
Differential Output Signal when
Disabled
Outputs AC-coupled, V
IN-MAX
applied to
input (Note 2)
K28.5 pattern at 4.25Gbps
K28.5 pattern at 3.2Gbps
Deterministic Jitter
(Notes 2, 3)
DJ
2
23
- 1 PRBS equivalent pattern at 2.7Gbps
(Note 4)
K28.5 pattern at 2.1Gbps
2
23
- 1 PRBS equivalent pattern at 155Mbps
Random Jitter
(Note 5)
Input = 5mV
P-P
Input = 10mV
P-P
20% to 80%, 4.25Gbps
3.1875GHz Bessel input filter
V
IN
= 20mV
P-P
20% to 80% (Note 2)
Input-Referred Noise
Low-Frequency Cutoff
Power-Supply Current
Power-Supply Noise Rejection
I
CC
PSNR
C
AZ
= open
C
AZ
= 0.1μF
(Note 6)
LOS disabled
f < 2MHz
26
8.7
8.5
9.3
7.8
25
6.5
3
60
86
185
70
0.8
32
49
37
115
μV
RMS
kHz
mA
dB
V
IN-MIN
V
IN-MAX
SYMBOL
CONDITIONS
Single ended to V
CC
Differential, f < 3GHz, DUT is powered on
(Note 1)
(Note 1)
Single ended to V
CC
Differential, f < 3GHz, DUT is powered on
600
1200
42
50
10
780
1200
10
25
25
30
25
50
ps
RMS
ps
P-P
58
dB
mV
P-P
mV
P-P
MIN
42
TYP
50
13
5
MAX
58
dB
mV
P-P
mV
P-P
UNITS
Data Output Transition Time
ps
2
_______________________________________________________________________________________
Compact 155Mbps to 4.25Gbps
Limiting Amplifier
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 2.97V to 3.63V, ambient temperature = -40°C to +85°C, CML output load is 50Ω to V
CC
, C
AZ
= 0.1µF, typical values are at
+25°C, V
CC
= 3.3V, unless otherwise specified. The data input transition time is controlled by a 4th-order Bessel filter with f
-3dB
=
0.75
✕
2.667GHz for all data rates of 2.667Gbps and below, and with f
-3dB
= 0.75
✕
data rate for data rates > 3.2Gbps.)
PARAMETER
LOS Hysteresis
LOS Assert/Deassert Time
LOS Assert
LOS Deassert
LOSS OF SIGNAL at 2.5Gbps
(Notes 2, 7)
LOS Hysteresis
LOS Assert/Deassert Time
Low LOS Assert Level
Low LOS Deassert Level
Medium LOS Assert Level
Medium LOS Deassert Level
High LOS Assert Level
High LOS Deassert Level
LOSS OF SIGNAL at 155Mbps
(Note 7)
LOS Hysteresis
LOS Assert/Deassert Time
Low LOS Assert Level
Low LOS Deassert Level
Medium LOS Assert Level
Medium LOS Deassert Level
High LOS Assert Level
High LOS Deassert Level
RSSI
RSSI Current Gain (Note 9)
Input-Referred RSSI Current
Stability
TTL/CMOS I/O
LOS Output High Voltage
LOS Output Low Voltage
LOS Output Current
DISABLE Input High
DISABLE Input Low
DISABLE Input Current
V
IH
V
IL
R
LOS
= 4.7k
to 10k
to V
CC_host
V
OH
V
OL
R
LOS
= 4.7k
R
LOS
= 4.7k
to10k
to10k
to V
CC_host
(3V)
to V
CC_host
(3.6V)
to V
CC_host
(3.3V);
2.0
0.8
10
2.4
0.4
40
V
V
μA
V
V
μA
A
RSSI
A
RSSI
= I
RSSI
/I
CM_RSSI
I
CM_INPUT
< 6.6mA
I
RSSI
/A
RSSI
(Note 10)
I
CM_INPUT
> 6.6mA
0.03
-31
-73
+33
+90
μA
10log (V
DEASSERT
/V
ASSERT
)
(Note 8)
R
TH
= 20k
R
TH
= 20k
R
TH
= 280
R
TH
= 280
R
TH
= 80
R
TH
= 80
2.1
20
3.5
5.6
13.3
21.2
33.3
55.5
dB
μs
mV
P-P
mV
P-P
mV
P-P
mV
P-P
mV
P-P
mV
P-P
10log (V
DEASSERT
/V
ASSERT
)
(Note 8)
R
TH
= 20k
R
TH
= 20k
R
TH
= 280
R
TH
= 280
R
TH
= 80
R
TH
= 80
22.8
10.3
1.25
2
2.8
4.1
6.7
15.2
25
38.3
65.2
99.3
38.6
11.6
2.2
100
dB
μs
mV
P-P
mV
P-P
mV
P-P
mV
P-P
mV
P-P
mV
P-P
SYMBOL
CONDITIONS
10log (V
DEASSERT
/V
ASSERT
)
(Note 8)
R
TH
= 280k
R
TH
= 280k
MIN
1.25
2
18.5
28
TYP
2.2
100
MAX
UNITS
dB
μs
mV
P-P
mV
P-P
MAX3748
LOSS OF SIGNAL at 4.25Gbps K28.5 pattern
(Note 2)
R
LOS
= 4.7k to10k
IC is powered down
Note 1:
Between sensitivity and overload, all AC specifications are met.
Note 2:
Guaranteed by design and characterization.
Note 3:
The deterministic jitter caused by this filter is not included in the DJ generation specifications (input).
_______________________________________________________________________________________
3
Compact 155Mbps to 4.25Gbps
Limiting Amplifier
MAX3748
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= 2.97V to 3.63V, ambient temperature = -40°C to +85°C, CML output load is 50Ω to V
CC
, C
AZ
= 0.1µF, typical values are at
+25°C, V
CC
= 3.3V, unless otherwise specified. The data input transition time is controlled by a 4th-order Bessel filter with f
-3dB
=
0.75
✕
2.667GHz for all data rates of 2.667Gbps and below, and with f
-3dB
= 0.75
✕
data rate for data rates > 3.2Gbps.)
Note 4:
2
23
- 1 PRBS pattern was substituted by K28.5 pattern to determine the high-speed portion of the deterministic jitter. The
low-speed portion of the DJ (baseline wander) was obtained by measuring the eye width difference between outputs gen-
erated using K28.5 and 2
23
- 1 PRBS patterns.
Note 5:
Random jitter was measured without using a filter at the input.
Note 6:
The supply current measurement excludes the CML output currents by connecting the CML outputs to a separate V
CC
(see Figure 1).
Note 7:
Unless otherwise specified, the pattern for all LOS detect specifications is 2
23
- 1 PRBS.
Note 8:
The signal at the input is switched between two amplitudes, Signal_ON and Signal_OFF, as shown in Figure 2.
Note 9:
I
CM_INPUT
is the input common mode. I
RSSI
is the current at the RSSI output.
Note 10:
Stability is defined as variation over temperature and power supply with respect to the typical gain of the part.
4
_______________________________________________________________________________________
Compact 155Mbps to 4.25Gbps
Limiting Amplifier
Typical Operating Characteristics
(T
A
= +25°C and V
CC
= 3.3V, unless otherwise specified.)
SUPPLY CURRENT
vs. TEMPERATURE
MAX3748 toc01
MAX3748
TRANSFER FUNCTION
MAX3748 toc02
RANDOM JITTER vs. TEMPERATURE
(INPUT LEVEL 10mV
P-P
)
9
8
RANDOM JITTER (ps
RMS
)
7
6
5
4
3
2
1
0
MAX3748 toc03
100
90
80
70
CURRENT (mA)
60
50
40
30
20
10
0
900
800
DIFFERENTIAL OUTPUT (mV
P-P
)
700
600
500
400
300
200
100
0
OUTPUT VOLTAGE vs. INPUT VOLTAGE
10
-40 -30-20 -10 0 10 20 30 40 50 60 70 80 90 100
TEMPERATURE (°C)
1
2
3
4
5
6
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100
TEMPERATURE (°C)
DIFFERENTIAL INPUT (mV
P-P
)
RANDOM JITTER
vs. INPUT AMPLITUDE
MAX3748 toc04
BIT-ERROR RATIO vs. INPUT VOLTAGE
MAX3748 toc05
DETERMINISTIC JITTER vs. INPUT
COMMON-MODE VOLTAGE (V
CC
TO V
CC
- 0.8V)
24
DETERMINISTIC JITTER (ps
P-P
)
22
20
18
16
14
12
10
MAX3748 toc06
10
9
8
RANDOM JITTER (ps
RMS
)
7
6
5
4
3
2
1
0
0
10
20
30
1200
1000
BIT-ERROR RATIO (10
-12
)
800
600
400
200
0
40
2.0
2.5
3.0
3.5
4.0
4.5
5.0
-1.0 -0.9 -0.8 -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0
COMMON-MODE VOLTAGE (V
CC
+ x)
DIFFERENTIAL INPUT AMPLITUDE (mV
P-P
)
INPUT VOLTAGE (mV
P-P
)
OUTPUT EYE DIAGRAM (MINIMUM INPUT)
MAX3748 toc07
OUTPUT EYE DIAGRAM (MAXIMUM INPUT)
MAX3748 toc08
OUTPUT EYE DIAGRAM (MINIMUM INPUT)
MAX3748 toc09
3.2Gbps, 2
23
- 1 PRBS, 5mV
P-P
3.2Gbps, 2
23
- 1 PRBS, 1200mV
P-P
2.7Gbps, 2
23
- 1 PRBS, 5mV
P-P
100mV/div
100mV/div
100mV/div
50ps/div
50ps/div
100ps/div
_______________________________________________________________________________________
5
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