19-2927; Rev 2; 11/05
2.7Gbps SFP Transimpedance
Amplifiers with RSSI
General Description
The MAX3744/MAX3745 transimpedance amplifiers pro-
vide a compact, low-power solution for communication
up to 2.7Gbps. They feature 330nA input-referred noise
at 2.1GHz bandwidth (BW) with 0.85pF input capaci-
tance. The parts also have >2mA
P-P
AC input overload.
Both parts operate from a single +3.3V supply and con-
sume 93mW. The MAX3744/MAX3745 are in a compact
30-mil x 50-mil die and require no external compensa-
tion capacitor. A space-saving filter connection is pro-
vided for positive bias to the photodiode through an
on-chip 580Ω resistor to V
CC
. These features allow
easy assembly into a low-cost TO-46 or TO-56 header
with a photodiode.
The MAX3744 and MAX3748A receiver chip set pro-
vides an RSSI output using a Maxim-proprietary inter-
face technique. The MAX3744 preamplifier, MAX3748A
postamplifier, and DS1858/DS1859 SFP controller meet
all the SFF-8472 digital diagnostic requirements.
♦
Up to 2.7Gbps (NRZ) Data Rates
♦
RSSI Implementation in 4-Pin TO-46 Header
(MAX3744)
♦
10ps
P-P
Deterministic Jitter for <100μA
P-P
Input
Current
♦
330nA
RMS
Input-Referred Noise at 2.1GHz
Bandwidth
♦
28mA Supply Current at +3.3V
♦
2GHz Small-Signal Bandwidth
♦
2.0mA
P-P
AC Overload
♦
Die Size: 30 mils x 50 mils
Features
MAX3744/MAX3745
Applications
Up to 2.7Gbps SFF/SFP Optical Receivers
Optimized for Small-Form-Factor Pluggable (SFP)
Optical Receivers
PART
MAX3744E/D
MAX3745E/D
Ordering Information
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
Dice**
Dice**
**Dice
are guaranteed to operate from -40°C to +85°C, but are
tested only at T
A
= +25°C.
Typical Application Circuit
SFP OPTICAL RECEIVER
400pF
400pF
V
CC
V
CC
FILTER OUT+
MAX3744
0.1
μ
F
OUT+
IN+
HOST
BOARD
IN
GND
OUT-
MAX3748A
IN-
OUT-
RSSI
DISABLE
LOS
0.1
μ
F
V
CC
= 3.3V
4.7kΩ
TO
10kΩ
4-PIN TO CAN
3.3k
Ω
MOD-DEF1
DS1858/
DS1859
MOD-DEF2
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
2.7Gbps SFP Transimpedance
Amplifiers with RSSI
MAX3744/MAX3745
ABSOLUTE MAXIMUM RATINGS
Power-Supply Voltage (V
CC
) .................................-0.5V to +6.0V
Continuous CML Output Current
(OUT+, OUT-) ............................................. -25mA to +25mA
Continuous Input Current (IN)...............................-4mA to +4mA
Continuous Input Current (FILTER).......................-8mA to +8mA
Operating Junction Temperature Range (T
J
) ....-55°C to +150°C
Storage Ambient Temperature Range (T
STG
) ...-55°C to +150°C
Die Attach Temperature...................................................+400°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 and T
A
= -40°C to +85°C. Typical values are at V
CC
= +3.3V, source capacitance (C
IN
) = 0.85pF, and T
A
=
+25°C, unless otherwise noted.) (Notes 1, 2)
PARAMETER
Supply Current
Input Bias Voltage
Input Overload
(Note 3)
C
IN
= 0.85pF, BW = 933MHz
C
IN
= 0.85pF, BW = 2.1GHz
Input-Referred Noise
I
N
C
IN
= 0.85pF, BW = 18GHz
C
IN
= 0.85pF, BW = 933MHz
C
IN
= 0.6pF, BW = 2.1GHz
C
IN
= 0.6pF, BW = 18GHz
Differential Transimpedance
Small-Signal Bandwidth (Note 3)
Low-Frequency Cutoff
Deterministic Jitter
(Notes 3, 5)
Filter Resistance
Differential Output Resistance
(OUT+, OUT-)
Maximum Differential Output
Voltage
V
OD
Input > 50µA
AVE
, output termination 50Ω to
V
CC
(output in limited state)
BW
Differential output, I
IN
= 40µA
AVE
-3dB, C
IN
= 0.6pF
-3dB, C
IN
= 0.85pF
-3dB, input current = 20µA
AVE
(Note 3)
100µA
P-P
< input
≤
2.1Gbps, K28.5 pattern
2mA
P-P
2.7Gbps, 2
31
-1 pattern
10µA
P-P
< input
≤
100µA
P-P
2.1Gbps, K28.5 pattern
2.7Gbps, 2
31
-1 pattern
510
85
220
14
24
10
20
580
100
280
690
115
400
Ω
Ω
mV
P-P
16
2.8
1.8
1.6
3.5
2
1.8
30
31
ps
P-P
206
300
380
550
4.5
kΩ
GHz
kHz
2
206
330
430
620
nA
RMS
SYMBOL
I
CC
CONDITIONS
Including CML output current (I
IN
= 0)
MIN
TYP
28
MAX
41
1.0
UNITS
mA
V
mA
P-P
DJ
2
_______________________________________________________________________________________
2.7Gbps SFP Transimpedance
Amplifiers with RSSI
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +2.97V to +3.63V and T
A
= -40°C to +85°C. Typical values are at V
CC
= +3.3V, source capacitance (C
IN
) = 0.85pF, and T
A
=
+25°C, unless otherwise noted.) (Notes 1, 2)
PARAMETER
Single-Ended Output Common-
Mode Minimum Level (MAX3744)
Output Data Transition Time
Differential Output Return Loss
Power-Supply Noise Rejection
RSSI Gain (MAX3744)
RSSI Gain Stability (MAX3744)
PSNR
A
RSSI
SYMBOL
CONDITIONS
Relative to V
CC
, I
IN
= 1mA
AVE
Input > 200µA
P-P
20% to 80% rise/fall time
(Note 3)
Frequency
≤
1GHz
1GHz < frequency
≤
2GHz
I
IN
= 0
(Note 6)
(Note 7)
10log(A
RSSI
/A
RSSI-NOM
) where A
RSSI-NOM
=
A
RSSI
at 3.3V, +25°C (Note 3)
f < 1MHz
1MHz
≤
f < 10MHz
MIN
540
TYP
490
80
17
10
46
34
21
0.24
140
MAX
UNITS
mV
ps
dB
dB
A/A
dB
MAX3744/MAX3745
Note 1:
Die parameters are production tested at room temperature only, but are guaranteed by design and characterization from
-40°C to +85°C.
Note 2:
Source capacitance represents the total capacitance at the IN pad during characterization of the noise and bandwidth para-
meters.
Note 3:
Guaranteed by design and characterization.
Note 4:
Input-referred noise is:
RMS output noise
Gain at f
=
100MHz
Note 5:
Deterministic jitter is the sum of pulse-width distortion (PWD) and pattern-dependent jitter (PDJ).
Note 6:
Power-supply noise rejection PSNR = -20log(∆V
OUT
/
∆V
CC
), where
∆V
OUT
is the differential output voltage and
∆V
CC
is the
noise on V
CC
.
Note 7:
I
OUT _ CM
(I
IN
=
400
µ
A)
−
I
OUT _ CM
(I
IN
=
0
µ
A)
A
RSSI
=
400
µ
A
+
I
OUT
−
I
where I
OUT _ CM
=
OUT
+
2
RSSI range is from I
IN
=
6
µ
A to 500
µ
A
_______________________________________________________________________________________
3
2.7Gbps SFP Transimpedance
Amplifiers with RSSI
MAX3744/MAX3745
Typical Operating Characteristics
(V
CC
= +3.3V, C
IN
= 0.85pF, T
A
= +25°C, unless otherwise noted.)
INPUT-REFERRED NOISE
vs. TEMPERATURE
MAX3744 toc01
INPUT-REFERRED NOISE
vs. TEMPERATURE
BW = 2.1GHz
INPUT-REFERRED NOISE (nA
RMS
)
700
600
500
C
IN
= 1.5pF
400
C
IN
= 0.85pF
300
C
IN
= 0.5pF
200
MAX3744 toc02
FREQUENCY RESPONSE
MAX3744 toc03
800
UNFILTER
INPUT-REFERRED NOISE (nA
RMS
)
700
600
C
IN
= 1.5pF
500
400
300
200
-40
-20
0
20
40
60
80
C
IN
= 0.85pF
C
IN
= 0.5pF
800
75
70
GAIN (dB)
65
60
55
50
-40
-20
0
20
40
60
80
100
10M
100M
1G
10G
TEMPERATURE (°C)
FREQUENCY (Hz)
100
TEMPERATURE (°C)
DETERMINISTIC JITTER
vs. INPUT AMPLITUDE
MAX3744 toc04
SMALL-SIGNAL TRANSIMPEDANCE
vs. TEMPERATURE
MAX3744 toc05
EYE DIAGRAM
INPUT = 20µA
P-P
, DATA RATE = 2.1Gbps
MAX3744 toc06
50
75
K28-5 PATTERN
DETERMINISTIC JITTER (ps
P-P
)
TRANSIMPEDANCE (dB
Ω)
40
70
5mV/div
65
30
2.7Gbp SONET
20
2.1Gbps FIBRE CHANNEL
10
0
0.01
0.1
1
10
INPUT AMPLITUDE (mA
P-P
)
60
-40
-20
0
20
40
60
80
100
60ps/div
TEMPERATURE (°C)
EYE DIAGRAM
INPUT = 20µA
P-P
, DATA RATE = 2.7Gbps
MAX3744 toc07
EYE DIAGRAM
INPUT = 2mA
P-P
, DATA RATE = 2.1Gbps
MAX3744 toc08
EYE DIAGRAM
INPUT = 2mA
P-P
, DATA RATE = 2.7Gbps
MAX3744 toc09
2
23
-1 PATTERN
K28-5 PATTERN
2
23
-1 PATTERN
6mV/div
30mV/div
30mV/div
60ps/div
60ps/div
60ps/div
4
_______________________________________________________________________________________
2.7Gbps SFP Transimpedance
Amplifiers with RSSI
MAX3744/MAX3745
Typical Operating Characteristics (continued)
(V
CC
= +3.3V, C
IN
= 0.85pF, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. TEMPERATURE
MAX3744 toc10
MAX3744 toc11
DIFFERENTIAL S22 vs. FREQUENCY
0
-5
MAX3744
-10
S22 (dB)
-15
-20
-25
-30
0
500 1000 1500 2000 2500 3000 3500 4000
FREQUENCY (MHz)
MAX3745
70
60
SUPPLY CURRENT (mA)
50
40
30
20
10
0
-40
-20
DC TRANSFER FUNCTION
(V
FILT
= 0V)
150
OUTPUT VOLTAGE (mV
P-P
)
100
50
0
-50
MAX3744 toc12
200
-100
-150
-200
0
20
40
60
80
100
-100
-50
0
50
100
TEMPERATURE (°C)
INPUT CURRENT (mA
P-P
)
RSSI
MAX3744, MAX3748A
MAX3744 toc13
BANDWIDTH vs. TEMPERATURE
MAX3744 toc14
EYE DIAGRAM
TEMPERATURE = +100°C INPUT = 20µA
P-P
DATA RATE = 2.7Gbps
MAX3744 toc15
550
T
A
= -40°C
500
MAX3748 RSSI OUTPUT (µA)
450
400
350
300
250
200
150
0
500
1000
1500
T
A
= +85°C
4.0
3.5
3dB BANDWIDTH (GHz)
3.0
2.5
2.0
1.5
1.0
0.5
0
-40
-20
0
20
40
60
80
C
IN
= 0.6pF
2
23
-1 PRBS
6mV/div
2000
100
60ps/div
AVERAGE INPUT CURRENT (µA)
TEMPERATURE (°C)
_______________________________________________________________________________________
5
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