MAXIM MAX3805ETE

19-2936; Rev 0; 7/03
10.7Gbps Adaptive Receive Equalizer
Features
♦ 3mm x 3mm Package
♦ Spans 30in (0.75m) of 6-mil FR-4
♦ Spans 24ft (8m) of Coax
♦ Automatic Receive Equalization to Reduce ISI
Caused by Path Losses
♦ Up to 10.7Gbps NRZ Data Operating Range
♦ Signal-Detect Output
♦ Output-Enable Control
♦ 135mW Power Consumption
♦ DC-Coupled Input and Output to Terminations as
Low as 1.65V
♦ Differential or Single-Ended Operation
♦ +3.3V Core Power Supply
Ordering Information
Applications
PART
OC-192, 10GbE Switches and Routers
OC-192, 10GbE Serial Modules
TEMP RANGE
MAX3805ETE
High-Speed Signal Distribution
PINPACKAGE
-40°C to +85°C 16 Thin QFN
PACKAGE
CODE
T1633F-3
Pin Configuration appears at end of data sheet.
Typical Operating Circuit
LINE CARD
SWITCH CARD
1.8V
2.5V
+3.3V
10Gbps
CDR/SERDES
2
+3.3V
VCC
2
2
SDO
VCC2
2.5V
SDI
FR-4 STRIPLINE
2
MAX3805
MAX3805
SD EN
10Gbps
SWITCH
VCC2
Rx
SDO
2
2
PC BOARD
BACKPLANE
Tx
Rx
VCC
VCC1
2
2
SDI
FR-4 STRIPLINE
Tx
SD EN VCC1
1.8V
________________________________________________________________ Maxim Integrated Products
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.
1
MAX3805
General Description
The MAX3805 is designed to provide up to 30in
(0.75m) reach on 6-mil differential FR-4 transmission
line, or up to 24ft (8m) on RG-188A/U type coaxial
cable, for PRBS data from 9.95Gbps to 10.7Gbps. The
MAX3805 adaptive equalizer reduces intersymbol interference, resulting in 20ps residual jitter after equalization. An internal feedback network controls the
equalizer to automatically match frequency-dependent
skin effect and dielectric losses. The MAX3805 provides LVCMOS-compatible output-enable and signaldetect functions.
The MAX3805 has separate supply connections for the
internal logic and I/O circuits. This allows the currentmode logic (CML) input and CML output to be connected to isolated supplies for independent DC-coupled
interfaces to 1.8V, 2.5V, or 3.3V ICs. The MAX3805
comes in a very small 3mm x 3mm package and consumes only 135mW.
MAX3805
10.7Gbps Adaptive Receive Equalizer
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (VCC) ............................................-0.5V to +4.0V
CML Supply Voltage
(VCC1, VCC2) ..........................................-0.5V to (VCC + 0.5V)
Current at SDO±...............................................................±25mA
SDI±, EN, SD, HFPD, LFPD........................-0.5V to (VCC + 0.5V)
Current at HFPD, LFPD ......................................................400µA
Continuous Power Dissipation (TA = +85°C)
16-Lead QFN-EP (derate 17.5mW/°C
above +85°C) ............................................................1398mW
Operating Ambient Temperature Range .............-40°C to +85°C
Storage Ambient Temperature Range...............-55°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°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.
OPERATING CONDITIONS
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
3.3
Supply Voltage
VCC
3.0
Input Termination Voltage
VCC1
1.65
Output Termination Voltage
VCC2
1.65
Operating Ambient Temperature
-40
+25
MAX
UNITS
3.6
V
VCC
V
VCC
V
+85
°C
ELECTRICAL CHARACTERISTICS
(Pin 13 (HFPD) and pin 14 (LFPD) are not connected. Typical values are at VCC = +3.3V, VCC1 = VCC2 = 1.8V, TA = +25°C, unless
otherwise noted.) (Values at -40°C are guaranteed by design and characterization.)
PARAMETER
SYMBOL
CONDITIONS
Supply Current
ICC
VCC = VCC1 = VCC2
CML Input Differential Voltage
VIN
AC-coupled or DC-coupled at transmission
line input (Notes 1, 6)
CML Input Common-Mode
Voltage
CML Input Resistance
Differential
CML Input Return Loss
100MHz to 10GHz
CML Output Differential Voltage
VOUT
CML Output Resistance
CML Output Transition Time
tr/tf
CML Output Return Loss
MIN
TYP
MAX
UNITS
41
60
mA
400
1200
mVP-P
1.3
VCC1
V
85
100
115
10
Ω
dB
VCC2 = 1.65V to 3.6V
400
500
600
mVP-P
Differential
85
100
115
Ω
20% to 80% (Notes 2, 6)
35
100MHz to 5GHz
10
Equalizer Time Constant
ps
dB
10
µs
Output Residual Jitter
(Notes 3–6)
21
Signal-Detect Assert
PRBS231 - 1 at 10.7Gbps (Note 1)
200
mVP-P
Signal-Detect Deassert
PRBS231 - 1 at 10.7Gbps (Note 1)
220
mVP-P
LVCMOS Input-High Leakage
Current
2
IH
+10
_______________________________________________________________________________________
30
+60
psP-P
µA
10.7Gbps Adaptive Receive Equalizer
(Pin 13 (HFPD) and pin 14 (LFPD) are not connected. Typical values are at VCC = +3.3V, VCC1 = VCC2 = 1.8V, TA = +25°C, unless
otherwise noted.) (Values at -40°C are guaranteed by design and characterization.)
PARAMETER
LVCMOS Input-Low Leakage
Current
SYMBOL
CONDITIONS
MIN
IL
-30
LVCMOS Input High
VIH
1.5
LVCMOS Input Low
VIL
LVCMOS Output High
VOH
IOH = 12.5µA
LVCMOS Output Low
VOL
IOL = 0.5mA
TYP
MAX
UNITS
+30
µA
0.5
V
V
2.1
V
0.2
V
Note 1: Differential input sensitivity is defined at the input to a transmission line with path length up to 30in.
Note 2: Measured using 10 ones and 10 zeros at 10.7Gbps.
Note 3: Residual jitter is the difference in total jitter between the signal at the input to the transmission line and the equalizer output.
Total residual jitter is DJP-P + 14.1 × RJRMS.
Note 4: Measured at 10.7Gbps using a pattern of 100 ones, PRBS 210 - 1, 100 zeros, PRBS 210 - 1.
Note 5: VIN = 400mVP-P to 1200mVP-P, input path is 0 to 30in, 6-mil microstrip in FR-4, εr = 4.5, and tan δ = 0.02.
Note 6: Guaranteed by design and characterization.
Typical Operating Characteristics
(VCC = 3.3V, VCC1 = 1.8V, VCC2 = 1.8V, and TA = +25°C, unless otherwise noted.)
EQUALIZER INPUT EYE AFTER 30in OF FR-4
(210 - 1PRBS WITH 100 CIDs AT 9.953Gbps)
EQUALIZER OUTPUT EYE AFTER 30in OF FR-4
(210 - 1PRBS WITH 100 CIDs AT 9.953Gbps)
MAX3805 toc02
MAX3805 toc01
65mV/div
65mV/div
20ps/div
EQUALIZER OUTPUT EYE AFTER 30in OF FR-4
(231 - 1PRBS AT 10.7Gbps)
MAX3805 toc03
65mV/div
20ps/div
20ps/div
_______________________________________________________________________________________
3
MAX3805
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics (continued)
(VCC = 3.3V, VCC1 = 1.8V, VCC2 = 1.8V, and TA = +25°C, unless otherwise noted.)
EQUALIZER OUTPUT EYE AFTER
24ft OF RG-188/U COAXIAL CABLE,
SINGLE ENDED (223 - 1PRBS AT 10.7Gbps)
MAX3805 toc04
SUPPLY CURRENT vs. TEMPERATURE
MAX3805 toc05
65
MAX3805 toc06
EQUALIZER OUTPUT EYE AFTER 30in OF FR-4
(CJTPAT 10.0Gbps LFPD/(HFPD + LFPD) = 0.6)
VCC = VCC1 = VCC2 = +3.3V
65mV/div
SUPPLY CURRENT (mA)
60
65mV/div
55
50
45
40
35
20ps/div
-40
20ps/div
-20
0
20
40
TEMPERATURE (°C)
DATA RATE = 9.953Gbps
PATTERN = PRBS 210 -1
40
35
RESIDUAL JITTER = DJ + 14.1 x RJ
30
FR4 = 30in
25
40
35
30
25
20
20
RESIDUAL JITTER = DJ + 14.1 x RJ
FR4 = 18in
15
400 500 600 700 800
12
15
18
21
24
RESIDUAL JITTER
vs. RLFPD/(RHFPD + RLFPD)
35
30
25
50
30in FR4
20
27
VIN = 400mVP-P
PATTERN = CJTPAT
DATA RATE = 10.0Gbps
(RLFPD + RHFPD) = 100kΩ
45
RESIDUAL JITTER (ps)
40
9
RESIDUAL JITTER vs. DATA RATE
VIN = 400mVP-P
PATTERN = 100 1's PRBS 210-1
100 0's PRBS 210-1
RESIDUAL JITTER = DJ + 14.1 x RJ
45
6
FR-4 PATH LENGTH (in)
MAX3805 toc09
50
3
900 1000 1100 1200
AMPLITUDE (mVP-P)
40
30
MAX3805 toc10
15
35
18in FR4
30
25
20
15
18in FR4
15
10
6
7
8
9
DATA RATE (Gbps)
4
DATA RATE = 10.7Gbps
PATTERN = PRBS 210 -1
VIN = 400mVP-P
45
RESIDUAL JITTER
RESIDUAL JITTER (ps)
45
50
MAX3805 toc07
50
MAX3805 toc08
RESIDUAL JITTER
vs. FR-4 PATH LENGTH
RESIDUAL JITTER vs. AMPLITUDE
RESIDUAL JITTER (ps)
MAX3805
10.7Gbps Adaptive Receive Equalizer
10
11
30in FR4
RESIDUAL JITTER = DJ + 14.1 x RJ
0.5
0.6
0.7
0.8
RLFPD/(RHFPD + RLFPD)
_______________________________________________________________________________________
0.9
60
80
10.7Gbps Adaptive Receive Equalizer
PIN
NAME
1
VCC1
FUNCTION
2
SDI+
Positive Differential Serial Data Input, CML
3
SDI-
Negative Differential Serial Data Input, CML
4
VCC1
Supply Voltage, CML Input (1.8V to VCC)
5
GND
6
SD
Signal-Detect Output, LVCMOS. Low indicates <200mVP-P, high indicates >220mVP-P.
7
EN
Enable Input, LVCMOS. Low disables output, high enables output, typically connected to SD.
8
GND
Supply Ground
9, 12
VCC2
Supply Voltage, CML Output (1.8V to VCC)
10
SDO-
Negative Differential Serial Data Output, CML
11
SDO+
Positive Differential Serial Data Output, CML
13
HFPD
High-Frequency Power Detector. Leave open for 9.953Gbps to 10.7Gbps PRBS NRZ data.
14
LFPD
Low-Frequency Power Detector. Leave open for 9.953Gbps to 10.7Gbps PRBS NRZ data.
15
VCC
Supply Voltage, CML Input (1.8V to VCC)
Supply Ground
Supply Voltage, Equalizer Core, 3.3V
16
GND
EP
Exposed
Pad
Supply Ground
Ground. The exposed pad must be soldered to the circuit board ground plane for proper thermal and
electrical performance.
Detailed Description and
Applications Information
The MAX3805 adaptive equalizer is designed to operate with 9.95Gbps to 10.7Gbps PRBS nonreturn-to-zero
(NRZ) data at the receive end of a transmission line,
typically differential 6-mil FR-4 PC board. It adaptively
corrects intersymbol interference caused by frequencydependent path loss. It can also be used with coaxial
cable links and with transmission lines that include wellengineered connectors, as long as the total path loss is
relatively smooth and does not exceed 20dB at 5GHz.
The signal path for the MAX3805 consists of a CML
input stage, two amplifiers feeding a pair of variable
attenuators controlled by feedback, and a limiting
amplifier with a CML output stage. An enable input, EN,
is used to control the output stage. A signal-detect output, SD, indicates when input signal to the transmission
line is above 220mVP-P or below 200mVP-P, typically.
See the Functional Diagram.
CML Input and Output Buffers
The MAX3805 CML input and output buffers are internally terminated with 50Ω to VCC1 and VCC2, respectively. The input and output circuitry have separate
voltage connections to control noise coupling and provide DC-coupling to +1.8V, +2.5V, or +3.3V CML. If
desired, the CML inputs and outputs can be AC-coupled. See Figure 1 for the output structure.
The low-frequency cutoff of the input-stage offset-cancellation circuit is nominally 21kHz.
For single-ended operation (typically coaxial cable
links), the input must be AC-coupled; connect the
unused input to VCC1 using a series combination of an
AC-coupling capacitor and a 50Ω resistor, as shown in
Figure 2. Note that the MAX3805 is specified for differential operation, and the performance may be reduced
in single-ended operation.
_______________________________________________________________________________________
5
MAX3805
Pin Description
10.7Gbps Adaptive Receive Equalizer
MAX3805
Functional Diagram
VCC1
VCC2
VCC
FLAT
AMP
VARIABLE
ATTENUATOR
SDO+
SDI+
∑
CML IN
LIMITING
AMP
CML OUT
SDI-
SDOVARIABLE
ATTENUATOR
POWER
DETECTOR
EN
LF POWER
DETECTOR
BOOST
AMP
MAX3805
SIGNAL
DETECT
LOOP
FILTER
LFPD
SD
HFPD
Input Stage with Equalization
The low-noise input stage of the MAX3805 includes two
amplifiers, one with flat frequency response and the
other with a highpass frequency response compensating for the loss characteristic of 6-mil FR-4 PC board
transmission line. A current-steering network, implemented with a pair of variable attenuators feeding into a
common summing node, provides the means to continuously vary the amount of equalization. The amount of
equalization is controlled by feedback from two powerdetector blocks that set the variable attenuators to
match the loss of a particular transmission path.
VCC
VCC2
50Ω
50Ω
OUT+
OUT-
ESD
STRUCTURES
Dual Power-Detector Feedback Loop
The MAX3805 adapts the equalizer to a specific path
loss by sampling the output of the summing node with a
pair of frequency-dependent power detectors. The first
power detector has a lowpass bandwidth of 500MHz; the
second power detector has full bandwidth.
NRZ PRBS data has a sin2(f)/f2 spectral characteristic.
When this data is passed through a lossy FR-4 path,
high-frequency components are attenuated, while low-
6
Figure 1. CML Output Structure
_______________________________________________________________________________________
10.7Gbps Adaptive Receive Equalizer
MAX3805
VCC
50Ω
TRANSMISSION LINE
0.01µF
500kΩ
IN+
VCC1
50Ω
0.01µF
MAX3805
LFPD
IN-
HFPD
MAX3805
Figure 2. Single-Ended Operation
Figure 3. Connecting a Potentionmeter Across HFPD and LFPD
frequency components remain essentially intact. These
changes in the spectral characteristic of the signal at
the output of the path are measured with the two power
detectors to provide a means to determine the path
loss.
The dual power-detector feedback loop measures the
ratio between the outputs of the two power detectors
and adjusts the attenuation to restore the sin 2 (f)/f 2
characteristic. The time constant for this feedback loop
is nominally 10µs.
Operating with Different Data Rates and
Codes
The MAX3805 equalizer feedback loop is optimized for
9.95Gbps to 10.7Gbps NRZ PRBS data; however, it
can also be used at a lower data rate or with a different
coding type by adjusting the feedback loop. The relative gain of the two power detectors can be adjusted by
connecting a 500kΩ trimmer potentiometer between
HFPD and LFPD pins, with the wiper connected to VCC,
as shown in Figure 3. Set the trimmer potentiometer for
the best eye opening.
Adding the potentiometer between HFPD and LFPD
can change the assert and deassert levels of the signal
detector, which could render the signal-detect output
invalid. For normal operation with 9.953Gbps to
10.7Gbps PRBS NRZ data, these signals should be left
open with no connections to pin 13 (HFPD) or pin 14
(LFPD). Note that excessive capacitance on pin 13 or
pin 14 can affect the operation of the feedback loop.
Make certain that the PC board traces from these pins
to the trimmer potentiometer are kept short.
Signal Detect
The output of the high-frequency power detector is
used to generate an LVCMOS-compatible signal-detect
(SD) output. The SD output asserts when the input signal at the transmission line falls below 200mVP-P, and
deasserts when the input signal at the transmission line
rises above 220mVP-P. The SD output can be directly
connected to the EN input to disable the MAX3805 output when no data signal is available. The SD output has
an LVCMOS fanout of one.
Package and Layout Considerations
The MAX3805 is packaged in a 3mm x 3mm plasticencapsulated 16-lead thin QFN package with exposed
pad for signal integrity. The exposed pad provides thermal and electrical connectivity to the IC, and must be
soldered to a high-frequency ground plane. Use good
layout techniques for the10Gbps SDI and SDO PC
board transmission lines, and configure the trace geometry near the IC package to minimize impedance discontinuities. Power-supply decoupling capacitors
should be provided for each supply connection and
located as close as practical to the IC package.
VCC
60kΩ
SD
Enable Function
The EN output is an LVCMOS-compatible pin that
enables the output stage of the MAX3805. Connect EN
to VCC or LVCMOS high to enable the output stage of
the device or to GND or LVCMOS low to disable the
output stage of the device.
ESD
STRUCTURES
Figure 4. Signal-Detect Output Circuit
_______________________________________________________________________________________
7
Pin Configuration
GND
VCC
LFPD
HFPD
Chip Information
TRANSISTOR COUNT: 1647
PROCESS: SiGe Bipolar
16
15
14
13
VCC1
1
12
VCC2
SDI+
2
11
SDO+
SDI-
3
10
SDO-
VCC1
4
9
VCC2
5
6
7
8
SD
EN
GND
MAX3805
GND
MAX3805
10.7Gbps Adaptive Receive Equalizer
*EXPOSED PAD IS CONNECTED TO GND
8
_______________________________________________________________________________________
10.7Gbps Adaptive Receive Equalizer
12x16L QFN THIN.EPS
D2
0.10 M C A B
b
D
D2/2
D/2
E/2
E2/2
CL
-A-
(NE - 1) X e
E
E2
L
-B-
k
e
CL
(ND - 1) X e
CL
CL
0.10 C
0.08 C
A
A2
A1
L
L
e
e
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE
12 & 16L, QFN THIN, 3x3x0.8 mm
APPROVAL
DOCUMENT CONTROL NO.
21-0136
REV.
C
1
2
_______________________________________________________________________________________
9
MAX3805
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
MAX3805
10.7Gbps Adaptive Receive Equalizer
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information,
go to www.maxim-ic.com/packages.)
EXPOSED PAD VARIATIONS
NOTES:
1. DIMENSIONING & TOLERANCING CONFORM TO ASME Y14.5M-1994.
2. ALL DIMENSIONS ARE IN MILLIMETERS. ANGLES ARE IN DEGREES.
3. N IS THE TOTAL NUMBER OF TERMINALS.
4. THE TERMINAL #1 IDENTIFIER AND TERMINAL NUMBERING CONVENTION SHALL CONFORM TO
JESD 95-1 SPP-012. DETAILS OF TERMINAL #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED
WITHIN THE ZONE INDICATED. THE TERMINAL #1 IDENTIFIER MAY BE EITHER A MOLD OR
MARKED FEATURE.
5. DIMENSION b APPLIES TO METALLIZED TERMINAL AND IS MEASURED BETWEEN 0.20 mm AND 0.25 mm
FROM TERMINAL TIP.
6. ND AND NE REFER TO THE NUMBER OF TERMINALS ON EACH D AND E SIDE RESPECTIVELY.
7. DEPOPULATION IS POSSIBLE IN A SYMMETRICAL FASHION.
8. COPLANARITY APPLIES TO THE EXPOSED HEAT SINK SLUG AS WELL AS THE TERMINALS.
9. DRAWING CONFORMS TO JEDEC MO220 REVISION C.
PROPRIETARY INFORMATION
TITLE:
PACKAGE OUTLINE
12 & 16L, QFN THIN, 3x3x0.8 mm
APPROVAL
DOCUMENT CONTROL NO.
21-0136
REV.
C
2
2
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
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Printed USA
is a registered trademark of Maxim Integrated Products.