19-5954; Rev 0; 7/11
EVALUATION KIT AVAILABLE
MAX3748H
Compact, Low-Power, 155Mbps to 4.25Gbps
Limiting Amplifier
General Description
The MAX3748H 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 controlled
edge speeds.
A received-signal-strength indicator (RSSI) is available
when the MAX3748H is combined with the MAX3744
SFP transimpedance amplifier (TIA). A receiver consist-
ing of the MAX3744 and the MAX3748H can provide up
to 19dB RSSI dynamic range. Additional features include
a programmable loss-of-signal (LOS) detect, an optional
disable function (DISABLE), and an output signal polar-
ity reversal (OUTPOL). Output disable can be used to
implement squelch.
The combination of the MAX3748H 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 MAX3748H is packaged in
a 3mm x 3mm, 16-pin thin QFN package with an exposed
pad.
S SFPReferenceDesignAvailable
S 16-PinTQFNPackagewith3mmx3mmFootprint
S Single3.3VSupplyVoltage
S 86psRiseandFallTime
S LossofSignalwithProgrammableThreshold
S RSSIInterface(withMAX3744TIA)
S OutputDisable
S PolaritySelect
S 8.7ps
P-P
DeterministicJitter(4.25Gbps)
Features
Applications
Gigabit Ethernet SFF/SFP Transceiver Modules
Fibre Channel SFF/SFP Transceiver Modules
Multirate OC-3 to OC-48-FEC SFF/SFP
Transceiver Modules
Ordering Information
appears 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
0.1µF
50Ω
0.1µF
50Ω
SerDes
V
CC
CAZ1
CAZ2
OUT+
OUT-
IN-
MAX3748H
RSSI
TH
R
TH
GND
DISABLE
LOS
4.7kΩ TO 10kΩ
V
CC_HOST
LOS
DS1858
3-INPUT DIAGNOSTIC
MONITOR
R1
3kΩ
C1
0.1µF
Typical Operating Circuits
continued at end of data sheet.
For related parts and recommended products to use with this part, refer to:
www.maxim-ic.com/MAX3748H.related
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Integrated Products
1
½
Forpricing,delivery,andorderinginformation,pleasecontactMaximDirectat1-888-629-4642,
orvisitMaxim’swebsiteatwww.maxim-ic.com.
MAX3748H
Compact, Low-Power, 155Mbps to 4.25Gbps
Limiting Amplifier
ABSOLUTEMAXIMUMRATINGS
Power-Supply Voltage Range (V
CC
) ....................-0.5V to +6.0V
Voltage Range at IN+, IN-............. (V
CC
- 2.4V) to (V
CC
+ 0.5V)
Voltage Range at DISABLE, OUTPOL,
RSSI, CAZ1, CAZ2, LOS, TH................ -0.5V to (V
CC
+ 0.5V)
Current Range into LOS ...................................... -1mA to +9mA
Differential Input Voltage (IN+ - IN-) ....................................2.5V
Continuous Current Range 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) ......................................+260°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional opera-
tion 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.
ELECTRICALCHARACTERISTICS
(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 T
A
= +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 x 2.667GHz for all data rates of 2.667Gbps and below, and with f
-3dB
= 0.75 x 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 1)
K28.5 pattern at 4.25Gbps
K28.5 pattern at 3.2Gbps
Deterministic Jitter
(Notes 1, 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)
Data Output Transition Time
Input-Referred Noise
Low-Frequency Cutoff
Power-Supply Current
Power-Supply Noise Rejection
I
CC
PSNR
C
AZ
= open
C
AZ
= 0.1FF
(Note 6)
LOS disabled
f < 2MHz
26
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 1)
8.7
8.5
9.3
7.8
25
6.5
3
60
86
185
70
0.8
32
49
37
115
FV
RMS
kHz
mA
dB
V
IN-MIN
V
IN-MAX
SYMBOL
CONDITIONS
Single-ended to V
CC
(Note 1)
Differential, f < 3GHz, DUT is powered on
(Note 2)
(Note 2)
Single-ended to V
CC
(Note 1)
Differential, f < 3GHz, DUT is powered on
1200
42
600
50
10
780
1200
10
25
25
30
25
55
ps
RMS
ps
P-P
58
MIN
42
TYP
50
13
5
MAX
58
UNITS
I
dB
mV
P-P
mV
P-P
I
dB
mV
P-P
mV
P-P
ps
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Integrated Products
2
½
MAX3748H
Compact, Low-Power, 155Mbps to 4.25Gbps
Limiting Amplifier
ELECTRICALCHARACTERISTICS(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 T
A
= +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 x 2.667GHz for all data rates of 2.667Gbps and below, and with f
-3dB
= 0.75 x data rate for data rates > 3.2Gbps.)
PARAMETER
LOS Hysteresis
LOS Assert/Deassert Time
LOS Assert
LOS Deassert
LOSSOFSIGNALAT2.5Gbps(Notes2,8)
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
LOSSOFSIGNALAT155Mbps(Note8)
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
Input-Referred RSSI Current
Stability
TTL/CMOSI/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
= 4.7kI to 10kI to V
CC_HOST
V
OH
V
OL
R
LOS
= 4.7kI to10kI to V
CC_HOST
(3V)
R
LOS
= 4.7kI to10kI to V
CC_HOST
(3.6V)
R
LOS
= 4.7kI to10kI to V
CC_HOST
(3.3V);
IC is powered down
2.0
0.8
10
2.4
0.4
40
V
V
FA
V
V
FA
A
RSSI
A
RSSI
= I
RSSI
/I
CM_RSSI
(Note 9)
I
CM_INPUT
< 6.6mA
I
RSSI
/A
RSSI
(Note 10)
I
CM_INPUT
> 6.6mA
0.03
-57
-118
+57
+112
FA
10log (V
DEASSERT
/V
ASSERT
)
(Note 7)
R
TH
= 20kI
R
TH
= 20kI
R
TH
= 280I
R
TH
= 280I
R
TH
= 80I
R
TH
= 80I
2.1
20
3.5
5.6
13.3
21.2
33.3
55.5
dB
Fs
mV
P-P
mV
P-P
mV
P-P
mV
P-P
mV
P-P
mV
P-P
10log (V
DEASSERT
/V
ASSERT
)
(Note 7)
R
TH
= 20kI
R
TH
= 20kI
R
TH
= 280I
R
TH
= 280I
R
TH
= 80I
R
TH
= 80I
22.8
10.3
1.25
2
4.8
7.7
15.2
25
38.3
65.2
99.3
38.6
13.6
2.2
100
dB
Fs
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 7)
R
TH
= 280kI
R
TH
= 280kI
MIN
1.25
2
18.5
28
TYP
2.2
100
MAX
UNITS
dB
Fs
mV
P-P
mV
P-P
LOSSOFSIGNALAT4.25GbpsK28.5PATTERN(Note1)
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Integrated Products
3
½
MAX3748H
Compact, Low-Power, 155Mbps to 4.25Gbps
Limiting Amplifier
ELECTRICALCHARACTERISTICS(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 T
A
= +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 x 2.667GHz for all data rates of 2.667Gbps and below, and with f
-3dB
= 0.75 x data rate for data rates > 3.2Gbps.)
Guaranteed by design and characterization.
Between sensitivity and overload, all AC specifications are met.
The deterministic jitter caused by this filter is not included in the DJ generation specifications (input).
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.
Note5:
Random jitter was measured without using a filter at the input.
Note6:
The supply current measurement excludes the CML output currents by connecting the CML outputs to a separate V
CC
(see
Figure 1).
Note7:
The signal at the input is switched between two amplitudes, Signal_ON and Signal_OFF, as shown in
Figure 2.
Note8:
Unless otherwise specified, the pattern for all LOS detect specifications is 2
23
- 1 PRBS.
Note9:
I
CM_INPUT
is the input common mode. I
RSSI
is the current at the RSSI output.
Note10:
Stability is defined as variation over temperature and power supply with respect to the typical gain of the part.
Note1:
Note2:
Note3:
Note4:
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Integrated Products
4
½
MAX3748H
Compact, Low-Power, 155Mbps to 4.25Gbps
Limiting Amplifier
Typical Operating Characteristics
(T
A
= +25°C and V
CC
= 3.3V, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
MAX3748H toc01
TRANSFER FUNCTION
MAX3748H toc02
RANDOM JITTER vs. TEMPERATURE
(INPUT LEVEL 10mV
P-P
)
9
RANDOM JITTER (ps
RMS
)
8
7
6
5
4
3
2
1
0
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100
TEMPERATURE (°C)
MAX3748H toc03
100
90
80
SUPPLY CURRENT (mA)
70
60
50
40
30
20
10
0
900
800
DIFFERENTIAL OUTPUT (mV
P-P
)
OUTPUT VOLTAGE vs. INPUT VOLTAGE
10
700
600
500
400
300
200
100
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90
TEMPERATURE (°C)
0
1
2
3
4
5
6
DIFFERENTIAL INPUT (mV
P-P
)
RANDOM JITTER
vs. INPUT AMPLITUDE
MAX3748H toc04
BIT-ERROR RATIO vs. INPUT VOLTAGE
MAX3748H 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
MAX3748H toc06
10
9
RANDOM JITTER (ps
RMS
)
8
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)
MAX3748H toc07
OUTPUT EYE DIAGRAM (MAXIMUM INPUT)
MAX3748H toc08
OUTPUT EYE DIAGRAM (MINIMUM INPUT)
MAX3748H 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
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Integrated Products
5
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