View MAX3793_323952.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

19-3467; Rev 0; 10/04
1Gbps to 4.25Gbps Multirate Transimpedance Amplifier with Photocurrent Monitor
General Description
The MAX3793 transimpedance amplifier provides a compact low-power solution for applications from 1Gbps up to 4.25Gbps. The MAX3793 features 195nA input-referred noise, 3.5k transimpedance gain, 2.9GHz bandwidth (CIN = 0.3pF) and 2.8mAP-P input overload. Operating from a +3.3V supply, the MAX3793 consumes only 106mW. An integrated filter resistor provides positive bias for the photodiode. These features, combined with a small die size, allow easy assembly into a TO-46 header with a photodiode. The MAX3793 also includes an average photocurrent monitor. The MAX3793 has a typical optical sensitivity of -20dBm (0.55A/W) at 4.25Gbps. Typical optical overload is at 4dBm. The MAX3793 and the MAX3794 limiting amplifiers provide a complete solution for multirate receiver applications. 4.7psP-P Deterministic Jitter (DJ) 195nARMS Input-Referred Noise 2.9GHz Small-Signal Bandwidth 2.8mAP-P AC Overload Photocurrent Output Monitor 3.5k Differential Gain Compact Die Size (30 mils x 50 mils)
Features
MAX3793
Applications
SFF/SFP Transceiver Modules from 1Gbps to 4.25Gbps Gigabit Ethernet Optical Receivers Multirate Fibre-Channel Optical Receivers
PART
Ordering Information
TEMP RANGE PIN-PACKAGE MAX3793E/D -40C to +85C Dice* *Dice are designed to operate from -40C to +85C ambient temperature, but are tested and guaranteed only at TA = +25C.
Typical Application Circuit
SFP OPTICAL RECEIVER CVCC HOST BOARD RATE_SELECT VCC IN+ BWSEL OUT+
CFILT FILT
VCC OUT+
0.1F
0.1F
MAX3793
IN MON GND OUT-
0.1F IN-
MAX3794*
OUT-
0.1F
VCC 4.7k TO 10k
DISABLE
LOS
RMON
MOD-DEF1
DS1856/ DS1859
*FUTURE PRODUCT
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.
1Gbps to 4.25Gbps Multirate Transimpedance Amplifier with Photocurrent Monitor MAX3793
ABSOLUTE MAXIMUM RATINGS
Power-Supply Voltage (VCC) .................................-0.5V to +4.5V 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 (TJ) ....-55C to +150C Storage Ambient Temperature Range (TSTG) ...-55C to +150C Die Attach Temperature...................................................+400C
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
(VCC = +2.97V to +3.63V, TA = -40C to +85C. Typical values are at VCC = +3.3V, source capacitance CIN = 0.60pF, TA = +25C, unless otherwise noted.) (Notes 1, 2)
PARAMETER Power-Supply Current Input Bias Voltage Input Overload Optical Input Sensitivity (850nm, re = 10dB, Responsiveness = 0.55A/W) IOL (Note 3) BER = 10-12 , K28.5, at 1.0625Gbps BER = 10-12 , K28.5, at 2.125Gbps BER = 10-12 , K28.5, at 4.25Gbps BW = 933MHz, 4th-order Bessel filter Input-Referred Noise (Notes 3, 4) Differential Transimpedance Small-Signal Bandwidth Gain Peaking Low-Frequency Cut-Off BW BW = 2000MHz, 4th-order Bessel filter Unfiltered output IIN = 20AAVE -3dB, CIN = 0.6pF (Note 3) -3dB, CIN = 0.3pF (Note 5) (Note 3) -3dB, IIN = 20AAVE (Note 3) IIN = 20AP-P, K28.5, at 4.25Gbps 20AP-P < IIN < 100AP-P, K28.5, at 4.25Gbps Deterministic Jitter (Notes 3, 6) DJ 100AP-P < IIN < 2.2mAP-P, K28.5, at 4.25Gbps TA = +100C 4.7 6 10 10 10 600 85 Outputs terminated by 50 to VCC, IIN > 100AP-P Outputs terminated by 50 to VCC 20% to 80%, IIN > 200AP-P (Note 3) 220 73 TA = +100C 90 750 100 930 115 480 95 ps mVP-P 2.8 1.9 2.36 2.2 2.8 -23.5 -23 -20 195 377 449 3.5 2.5 2.9 0 70 11 16 27 psP-P 264 420 615 4.5 3.2 3.56 k GHz dB kHz nARMS dBm SYMBOL ICC CONDITIONS Measured with AC-coupled output MIN TYP 32 MAX 46 1.0 UNITS mA V mAP-P
TA = +100C, 100AP-P < IIN < 2.2mAP-P, K28.5, at 4.25Gbps Photodiode Resistor Differential Output Resistance Maximum Differential Output Voltage Output Edge Transition Time RFILT ROUT VOD(MAX)
2
_______________________________________________________________________________________
1Gbps to 4.25Gbps Multirate Transimpedance Amplifier with Photocurrent Monitor
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +2.97V to +3.63V, TA = -40C to +85C. Typical values are at VCC = +3.3V, source capacitance CIN = 0.60pF, TA = +25C, unless otherwise noted.) (Notes 1, 2)
PARAMETER Differential Output Return Loss Single-Ended Output Return Loss Power-Supply Noise Rejection (Note 7) Minimum Photocurrent to be Detected Maximum Photocurrent to be Detected Maximum Photocurrent Monitor Output Offset Photocurrent Monitor Output Offset Temperature Dependency Monitor Output Compliance Voltage Photocurrent Monitor Gain Photocurrent Monitor Gain Stability Photocurrent Monitor Gain Bandwidth PSNR IAVGMIN IAVGMAX IMON
(OFFSET)
MAX3793
SYMBOL
CONDITIONS Frequency 1GHz 1GHz < frequency 4GHz Frequency 1GHz 1GHz < frequency 4GHz IIN = 0, f < 1MHz IIN = 0, 1MHz f < 10MHz
MIN
TYP 18 9 14 11 47 22
MAX
UNITS dB dB dB
2 1 IIN = 0AP-P IIN = 0AP-P IMON(OFFSET) = ABS (IMON(OFFSET) (-40C) - IMON(OFFSET) (+100C)) 0 2A IAVG 1.0mA 2A IAVG 1.0mA (Notes 3, 8) 2A IAVG 1.0mA -10 7 1 +10 10
A mA A
IMON
(OFFSET)
0.21
A
VMON AMON
2
V A/A % MHz
Note 1: Die parameters are production tested at room temperature only, but are guaranteed by design and characterization from -40C to +85C. Note 2: Source capacitance represents the total external capacitance at the IN pad during characterization of the noise and bandwidth parameters. Note 3: Guaranteed by design and characterization. Note 4: Input-referred noise is: RMS Output Noise Gain at f = 100MHz Note 5: Values are derived by calculation from the CIN = 0.6pF measurements. Note 6: DJ is the sum of pulse-width distortion (PWD) and pattern-dependent jitter (PDJ). DJ is measured using a 3.2GHz 4th-order Bessel filter on the input. Note 7: Power-supply noise rejection PSNR = -20log(VOUT / VCC), where VOUT is the change in differential output voltage and VCC is the noise on VCC. Note 8: Gain stability is defined as (AMON - AMON-NOM) / (AMON-NOM) over the listed current range, temperature, and supply variation. Nominal gain is measured at VCC = +3.3V and +25C.
_______________________________________________________________________________________
3
1Gbps to 4.25Gbps Multirate Transimpedance Amplifier with Photocurrent Monitor MAX3793
Typical Operating Characteristics
(VCC = +3.3V, CIN = 0.6pF, TA = +25C, unless otherwise noted.)
INPUT-REFERRED NOISE vs. TEMPERATURE
MAX3793 toc01
FREQUENCY RESPONSE
MAX3793 toc02
DETERMINISTIC JITTER vs. INPUT AMPLITUDE
DATA RATE = 4.25Gbps K28.5 PATTERN, UNFILTERED INPUT
MAX3793 toc03
600 INPUT-REFERRED NOISE (nARMS)
75
18 15 12 9 6 3 0
500 UNFILTERED
400
65
300 BW = 2.0GHz 200
60
55
100 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
50 10M 100M 1G 10G FREQUENCY (Hz)
DETERMINISTIC JITTER (psP-P)
70 GAIN (dB)
20
400
800
1.2m
1.6m
2.0m
INPUT AMPLITUDE (AP-P)
SMALL-SIGNAL TRANSIMPEDANCE vs. TEMPERATURE
MAX3793 toc04
DIFFERENTIAL S22 vs. FREQUENCY
-5 -10 -15 S22 (dB) -20 -25 -30
MAX3793 toc05
SUPPLY CURRENT vs. TEMPERATURE
MAX3793 toc06
75
0
70 60 SUPPLY CURRENT (mA) 50 40 30 20 10 0
TRANSIMPEDANCE (dB)
70
65
-35 -40 -45
60 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
-50 10M 100M 1G 10G FREQUENCY (Hz)
-40
-20
0
20
40
60
80
100
TEMPERATURE (C)
MONITOR OUTPUT CURRENT vs. AVERAGE INPUT CURRENT
MAX3793 toc07
DC TRANSFER FUNCTION (VFILT = 0V)
150 OUTPUT VOLTAGE (mV) 100 50 0 -50 -100
MAX3793 toc08
1.0 MONITOR OUTPUT CURRENT (mA)
200
0.8
0.6
0.4
0.2 -150 0 0 0.2 0.4 0.6 0.8 1.0 AVERAGE INPUT CURRENT (mA) -200 -100 -50 0 50 100 INPUT CURRENT (A)
4
_______________________________________________________________________________________
1Gbps to 4.25Gbps Multirate Transimpedance Amplifier with Photocurrent Monitor
Typical Operating Characteristics (continued)
(VCC = +3.3V, CIN = 0.6pF, TA = +25C, unless otherwise noted.)
MAX3793
EYE DIAGRAM INPUT = 20AP-P, DATA RATE = 1.0625Gbps
MAX3793 toc09
EYE DIAGRAM INPUT = 20AP-P, DATA RATE = 2.125Gbps
MAX3793 toc10
EYE DIAGRAM INPUT = 20AP-P, DATA RATE = 4.25Gbps
MAX3793 toc11
K28.5 PATTERN
K28.5 PATTERN
K28.5 PATTERN
10mV/div
10mV/div
10mV/div
200ps/div
100ps/div
48ps/div
EYE DIAGRAM INPUT = 2.2mAP-P, DATA RATE = 4.25Gbps
MAX3793 toc12
EYE DIAGRAM TA = +100C INPUT = 20AP-P, DATA RATE = 4.25Gbps
MAX3793 toc13
PHOTOCURRENT MONITOR OFFSET TEMPERATURE DEPENDENCY HISTOGRAM
40 35 % OF UNITS 30 25 20 15 10 5 0
MAX3793 toc14
K28.5 PATTERN
K28.5 PATTERN
45
40mV/div
10mV/div
48ps/div
48ps/div
0-0.14
0.28-0.42 0.56-0.7 0.14-0.28 0.7-0.84 0.42-0.56 IMON CHANGE OVER TEMPERATURE (A)
_______________________________________________________________________________________
5
1Gbps to 4.25Gbps Multirate Transimpedance Amplifier with Photocurrent Monitor MAX3793
Pin Description
BOND PAD 1 2, 3 4 5 6 7, 11 8, 10 9 NAME OUT+ VCC FILT IN MON GND N.C. OUTFUNCTION Noninverting Data Output. Current flowing into IN causes the voltage at OUT+ to increase. +3.3V Supply Voltage. The pads are not internally connected. Therefore, they must always be externally bonded. Provides bias voltage for the photodiode through a 750 resistor to VCC. When grounded, this pin disables the DC-cancellation amplifier to allow a DC path from IN to OUT+ and OUT- for testing. TIA Input. Signal current from photodiode flows into this pin. Photocurrent Monitor. Output current from MON is proportional to the average current in RFILT. Connect a resistor between MON and ground to monitor the average photocurrent. Circuit Ground. The pads are not internally connected. Therefore, they must always be externally bonded. No Connection Inverting Data Output. Current flowing into IN causes the voltage at OUT- to decrease.
See the Wire Bonding section for recommended bonding sequence, Figure 4.
Functional Diagram
VCC
Rf
VOLTAGE AMPLIFIER
OUTPUT ROUT BUFFER
ROUT OUT+
IN
TIA
OUT-
LOWPASS FILTER
MAX3793
DC CANCELLATION VCC FILTER NETWORK
EN FILT MON
6
_______________________________________________________________________________________
1Gbps to 4.25Gbps Multirate Transimpedance Amplifier with Photocurrent Monitor MAX3793
AMPLITUDE AMPLITUDE INPUT FROM PHOTODIODE
TIME OUTPUT (SMALL SIGNALS) INPUT AFTER DC CANCELLATION OUTPUT (LARGE SIGNALS)
TIME
Figure 1. MAX3793 Limited Output
Figure 2. DC-Cancellation Effect on Input
Detailed Description
The MAX3793 transimpedance amplifier is designed for 1Gbps to 4.25Gbps fiber optic applications. The MAX3793 is comprised of a transimpedance amplifier, a voltage amplifier, an output buffer, a DC-cancellation circuit, a photodiode biasing resistor, and a photocurrent monitor (see the Functional Diagram).
The DC-cancellation circuit is internally compensated and does not require external capacitors. This circuit minimizes pulse-width distortion for data sequences that exhibit a 50% mark density. A mark density significantly different from 50% causes the MAX3793 to generate pulse-width distortion. Grounding the FILT pin disables the DC-cancellation circuit. For normal operation, the DC-cancellation circuit must be enabled.
Transimpedance Amplifier
The signal current at the input flows into the summing node of a high-gain amplifier. Shunt feedback through resistor RF converts this current into a voltage. Schottky diodes clamp the output signal for large input currents (Figure 1).
Photocurrent Monitor
The MAX3793 includes an average photocurrent monitor. The current sourced from MON to ground is proportionally equal to the average R FILT current (see the Typical Operating Characteristics). This RFILT is used to bias the photodiode, see Figure 7. RFILT is an internal 750 resistor between V CC and FILT. This resistor is to be used in conjunction with an external C FILT to bias the photodiode. The current through this resistor is monitored and creates the photocurrent monitor output. For test purposes, driving FILT below 0.5V disables the DC-cancellation circuit.
Voltage Amplifier
The voltage amplifier provides additional gain and converts the transimpedance amplifier single-ended output signal into a differential signal.
Output Buffer
The output buffer is designed to drive a 100 differential load between OUT+ and OUT-. For optimum supply noise rejection, the MAX3793 should be terminated with a matched load. The MAX3793 outputs do not drive a DC-coupled grounded load. The outputs should always be AC-coupled. Refer to Application Note HFAN-1.1: Choosing AC-Coupling Capacitors for a more detailed discussion on selecting capacitors. If a single-ended output is required, both the used and the unused outputs should be terminated in a similar manner. See Figure 6.
Design Procedure
Select Photodiode
Noise performance and bandwidth are adversely affected by capacitance on the TIA input node. Select a low-capacitance photodiode to minimize the total input capacitance on this pin. The MAX3793 is optimized for 0.6pF of capacitance on the input.
Select CFILT
The filter resistor of the MAX3793, combined with an external capacitor, can be used to reduce noise (see the Typical Application Circuit). Current generated by supply noise voltage is divided between CFILT and CIN. Assuming the filter capacitor is much larger than the photodiode capacitance, the input noise current due to supply noise is: INOISE = (VNOISE x CIN) / (RFILT x CFILT)
7
DC-Cancellation Circuit
The DC-cancellation circuit uses low-frequency feedback to remove the DC component of the input signal (Figure 2). This feature centers the input signal within the transimpedance amplifier's linear range, thereby reducing pulse-width distortion.
_______________________________________________________________________________________
1Gbps to 4.25Gbps Multirate Transimpedance Amplifier with Photocurrent Monitor MAX3793
If the amount of tolerable noise is known, the filter capacitor can be easily selected: CFILT = (VNOISE x CIN) / (RFILT x INOISE) For example, with maximum noise voltage = 100mVP-P, CIN = 0.6pF, RFILT = 750, and INOISE at 350nA, the filter capacitor is: CFILT = (100mV x 0.6pF) / (750 x 350nA) = 229pF RMON = 2.0V IMONMAX
where, IMONMAX is the largest average input current observed. An ammeter can also be used to monitor the current out of the MON pin.
Select RMON
If photocurrent monitoring is desired, connect a resistor between MON and ground to monitor the average photocurrent. Select the largest RMON possible:
Layout Considerations
Figure 3 shows suggested layouts for 4-pin and 5-pin TO headers.
Wire Bonding
For high-current density and reliable operation, the MAX3793 uses gold metalization. For best results, use gold-wire ball-bonding techniques. Exercise caution if attempting wedge bonding. The die size is 30 mils x 50 mils (0.762mm x 1.27mm), and the die thickness is 15 mils (380m). Bond-pad size for the VCC, GND, OUT+, and OUT- pads is 94m x 94m. Bond-pad size for the FILT, IN, and MON pads is 79m x 79m; all bond-pad metal thickness is 1.2m. Refer to Maxim Application Note HFAN-08.0.1: Understanding Bonding Coordinates and Physical Die Size for additional information on bondpad coordinates. Recommended bonding sequence is shown in Figure 4.
MON PHOTODIODE CFILT 5-PIN HEADER OUTFILT IN MON
VCC
CVCC OUT+
MAX3793
PHOTODIODE IS MOUNTED ON CFILT, CASE IS GROUND.
11 CFILT 1
VCC PHOTODIODE CFILT 4-PIN HEADER OUTCVCC OUT+
7
10 3 2 5 6
CVCC
9
8
MAX3793
Figure 3. Suggested TO Header Layouts 8
_______________________________________________________________________________________
FILT IN MON
4
PHOTODIODE IS MOUNTED ON CFILT, CASE IS GROUND.
MAX3793
Figure 4. Recommended MAX3793 Bonding Scheme
1Gbps to 4.25Gbps Multirate Transimpedance Amplifier with Photocurrent Monitor
Applications Information
Optical Power Relations
Many of the MAX3793 specifications relate to the input signal amplitude. When working with optical receivers, the input is sometimes expressed in terms of average optical power and extinction ratio. Figure 5 and Table 1 show relations that are helpful for converting optical power to input signal when designing with the MAX3793. To obtain a system bit-error rate (BER) of 1E-12, the signal-to-noise ratio must always exceed 14:1. The input sensitivity, expressed in average power, can be estimated as:
14.1 x IN (re + 1) Sensitivity = 10 log x 1000 dBm 2 x x (re - 1))
MAX3793
where, is the photodiode responsivity in A/W, and IN is the RMS noise current in amps.
Optical Sensitivity Calculation
The input-referred RMS noise current (I N ) of the MAX3793 generally determines the receiver sensitivity.
Input Optical Overload
Overload is the largest input that the MAX3793 accepts while meeting DJ specifications. Optical overload can be estimated in terms of average power with the following equation: I Overload = 10log OL x 1000 dBm 2 x
PI
OPTICAL POWER
PAVG
Optical Linear Range
The MAX3793 has high gain, which limits the output when the input signal exceeds 50AP-P. The MAX3793 operates in a linear range for inputs not exceeding:
50A x (re + 1) Linear Range = 10 log x 1000 dBm 2 x x (re - 1)
PO
TIME
Figure 5. Optical Power Relations
Table 1. Optical Power Relations*
PARAMETER Average power Extinction ratio Optical power of a 1 Optical power of a 0 Optical modulation amplitude SYMBOL PAVG re P1 P0 PIN RELATION PAVG = (P0 + P1) / 2 re = P1 / P0
P1 = 2PAVG
re re + 1
P0 = 2PAVG / (re + 1)
PIN = P1 - P0 = 2PAVG re -
re +
*Assuming a 50% average mark density.
_______________________________________________________________________________________
9
1Gbps to 4.25Gbps Multirate Transimpedance Amplifier with Photocurrent Monitor MAX3793
Interface Schematics
VCC VCC VCC 50 50 OUT+ VCC FILT
VCC
RFILT 750
750
OUTVCC
MON
Figure 6. Equivalent Output
Figure 7. FILT and MON Interface
Table 2. Bond-Pad Coordinates
PAD BP1 BP2 BP3 BP4 BP5 BP6 BP7 BP8 BP9 BP10 BP11 NAME OUT+ VCC VCC FILT IN MON GND N.C. OUTN.C. GND COORDINATES (m) X 40.2 40.2 47.2 166.2 278.2 390.2 509.2 516.2 509.2 393.0 274.0 Y 650.6 391.6 47.2 40.2 40.2 40.2 47.2 289.2 650.6 1032.8 1025.8
Pad Coordinates
Table 2 gives center pad coordinates for the MAX3793 bondpads. See Application Note HFAN-8.0.1: Understanding Bonding Coordinates and Physical Die Size for more information on bondpad coordinates.
Chip Information
TRANSISTOR COUNT: 475 PROCESS: SiGe Bipolar
Package Information
For the latest package outline information, go to www.maxim-ic.com/packages.
10
______________________________________________________________________________________
1Gbps to 4.25Gbps Multirate Transimpedance Amplifier with Photocurrent Monitor
Pin Configuration/Chip Topography
GND N.C.
MAX3793
11
10
HD682-A
OUT+ 1 VCC 2 VCC 3 4 FILT
MAX3793
9
OUT-
8
N.C.
5
6
7
GND
IN
MON
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 11 (c) 2004 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

▲Up To Search▲

Price & Availability of MAX3793

	To Download MAX3793 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .