Optical Evaluation Kit for the ADN2525 EVAL-ADN2525-NT/ADN2525-OP GENERAL DESCRIPTION This data sheet describes the optical evaluation kit for the ADN2525, a 10 Gbps, active back-termination, differential laser diode driver. The differential configuration of the output stage combined with on-chip active back-termination ensures high quality eye diagrams at lower power consumption compared with traditional approaches on 10 Gbps laser diode drivers. Complete specifications can be found in the ADN2525 data sheet available from Analog Devices, Inc., and should be consulted in conjunction with this data sheet when using the evaluation board. The EVAL-ADN2525-OP evaluation kit consists of an evaluation board that provides optical evaluation of the ADN2525 with an Opnext 10 Gbps 1310 nm TOSA (LD5033SMDL). The EVAL-ADN2525-NT evaluation kit consists of the same evaluation board without a TOSA attached. To evaluate the performance of the ADN2525, the board must be connected to the test setup as shown in Figure 1. A fiber patch cord with an appropriate connector for the TOSA end is required to connect the TOSA to the oscilloscope. The power supply must be able to deliver 400 mA at 3.3 V. The amplitude of the data signal from the pattern generator must be adjusted to within the ADN2525 data sheet specifications for data inputs, typically 1 V peak-to-peak differential (500 mV single-ended on DATAP and DATAN). The oscilloscope/digital communications analyzer must have a 1310 nm optical channel that can accept and display properly the optical signals generated by the TOSA. The coaxial cables used to connect the pattern generator to the evaluation board DATAP/DATAN inputs must be suitable for carrying 10 Gbps signals without significant reduction of rise/fall time or introduction of pattern jitter. They should also be a matched pair with a delay skew of ≤2 ps. An example of suitable cables is the 60 cm Lab-Flex® 160 cables with 2.4 mm connectors from Florida RF Labs. Z0 = 50Ω TRIGGER OUT TRIGGER IN Z0 = 50Ω J6 OPTICAL EVALUATION BOARD PATTERN GENERATOR DATA OPTICAL FIBER ADN2525 Z0 = 50Ω J5 TOSA J2 J4 J1 POWER SUPPLY 0V TO 1.2V/2mA POWER SUPPLY 3.3V/400mA POWER SUPPLY 0V TO 1.2V/2mA BSET VCC MSET OSCILLOSCOPE/ DIGITAL COMMUNICATIONS ANALYZER 06368-001 DATA Figure 1. ADN2525 Optical Evaluation Board Test Setup Rev. 0 Evaluation boards are only intended for device evaluation and not for production purposes. Evaluation boards are supplied “as is” and without warranties of any kind, express, implied, or statutory including, but not limited to, any implied warranty of merchantability or fitness for a particular purpose. No license is granted by implication or otherwise under any patents or other intellectual property by application or use of evaluation boards. Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Analog Devices reserves the right to change devices or specifications at any time without notice. Trademarks and registered trademarks are the property of their respective owners. Evaluation boards are not authorized to be used in life support devices or systems. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.461.3113 ©2007 Analog Devices, Inc. All rights reserved. EVAL-ADN2525-NT/ADN2525-OP TABLE OF CONTENTS General Description ......................................................................... 1 Revision History ............................................................................... 2 Using the Evaluation Board PCB Layout in an Optical Transmitter design. .......................................................................5 Evaluation Board Hardware ............................................................ 3 Evaluation Board Schematics and Artwork...................................6 Connectors .................................................................................... 3 Ordering Information.......................................................................8 Terminals ....................................................................................... 3 Bill of Materials..............................................................................8 Jumpers .......................................................................................... 3 Ordering Guide .............................................................................8 Quick Start for Optical Evaluation............................................. 4 ESD Caution...................................................................................8 REVISION HISTORY 7/07—Revision 0: Initial Version Rev. 0 | Page 2 of 8 EVAL-ADN2525-NT/ADN2525-OP EVALUATION BOARD HARDWARE TOP LAYER 6 The ADN2525 is capable of delivering an 80 mA differential modulation current and 100 mA bias current. Applying dc voltages to the ADN2525 BSET and MSET pins sets the bias and modulation currents. The board is set up so that the outputs of the ADN2525 are ac-coupled to the TOSA. The board is fitted with connectors that allow the user to connect the evaluation board to the test setup. Table 1 describes the name and function of each connector on the board. J2 J3 J4 J5 J6 J9 2 1 For additional optical eye diagram performance data and for information on optimizing the performance of the evaluation board for different TOSAs, contact a local Analog Devices representative. JUMPERS Automatic laser shutdown is configurable, driven either by voltages generated on the board or by external voltages as described in Table 3. Table 3. Jumper Configurations Jumper P4 TERMINALS The evaluation board accommodates the terminal assignment of the multisource agreement for the 10 Gbps XMD miniature device (EVAL-ADN2525-OP). Table 2. XMD MSA TOSA Terminal Function Definition Option 1 PD Cathode Signal Ground LD Cathode LD Anode Signal Ground Thermistor 3 Figure 2. Pinout of TOSA Footprint on PCB (Looking Toward the Edge of the Board Cross Section) Description Allows the user to apply an external dc voltage source to control the differential modulation current provided by the ADN2525. Allows the user to apply an external dc voltage source to control the bias current provided by the ADN2525. Automatic Laser Shutdown. Allows the user to enable/disable the bias and modulation current by applying a low/high logic level (not greater than VCC). Power Supply Connector. The board supply voltage is 3.3 V with respect to GND. Negative data input. A PECL/CML data signal should be applied. Positive Data Input. A PECL/CML data signal should be applied. 25 Ω Test Transmission Line. Terminal Number 1 2 3 4 5 6 4 BOTTOM LAYER Table 1. Connector Description Connector J1 5 06368-002 CONNECTORS Option 2 PD Cathode Signal Ground LD Cathode LD Anode Signal Ground NC Rev. 0 | Page 3 of 8 Jumper Setting A B Removed Configuration Description Enables the bias and differential modulation currents. Disables the bias and differential modulation currents. Allows the user to enable/disable the bias and differential modulation currents by applying a low/high logic level to J3 from an external source. EVAL-ADN2525-NT/ADN2525-OP QUICK START FOR OPTICAL EVALUATION 1. 2. 3. 4. 5. 6. 7. 8. If using evaluation kit EVAL-ADN2525-NT, solder a TOSA to the evaluation board, following soldering guidelines in the TOSA data sheet. If required, change the ALS jumper settings to obtain the desired configuration, using Table 3. Connect the evaluation board to an oscilloscope, pattern generator, and power supplies as shown in Figure 1. A suitable pattern generator is the Anritsu MP1763B and a suitable oscilloscope is the Agilent 86100B with 86105C optical plug-in. Use coaxial cables for DATAP and DATAN of the type recommended in the General Description section. Run any applicable user calibrations on the oscilloscope optical input. Turn on the power supply (3.3 V) connected to J4. Check that the current drawn from the 3.3 V power supply is within the limits of the ISUPPLY specifications in the ADN2525 data sheet. Increase the voltage applied to J2 starting from 0 V until the desired optical average power is obtained. Increase the voltage applied to J1 starting from 0 V until the desired extinction ratio is obtained. To prevent damage to the TOSA, it is advisable to gradually adjust the BSET and MSET voltages back to 0 V before turning off the power supplies. 6. 7. 8. 9. Using the EVAL-ADN2525-OP Evaluation Kit When using the EVAL-ADN2525-OP evaluation kit, it is recommended that the kit be initially set up to reproduce the sample optical eye diagram that is included with the kit. This confirms that the test setup is configured correctly to produce a high quality optical eye diagram. The following steps should be followed to reproduce the sample optical eye diagram: 1. 2. 3. 4. 5. Set up the board following the recommendations in the Quick Start for Optical Evaluation section. Adjust the data rate and pattern to the settings used in the sample optical eye diagram and select the appropriate optical filter and wavelength on the oscilloscope. Adjust the BSET and MSET voltages to the settings used in the sample optical eye diagram. Confirm that the VCC supply current (ICC) and the IBMON voltage at TP1 are close to the values reported in the sample optical eye diagram. If either of the values is significantly different, this indicates that there is a problem with the test setup, evaluation board, or TOSA, and this should be investigated. Confirm that the real average power is close to the value reported in the sample optical eye diagram. The real average power is the average power as measured by the test equipment plus the measured attenuation of any optical attenuators in the optical signal path. If the value is significantly different, this indicates that there is a problem with the test setup, evaluation board, or TOSA, and this Rev. 0 | Page 4 of 8 should be investigated. Less significant differences can sometimes be attributed to one or more of the following: a. Dirt in the fiber connectors, optical attenuators, or oscilloscope optical input can cause errors in average power. b. Optical coupling can be quite variable at the TOSA because there is no latching mechanism for the fiber connector. By ensuring that the connector is fully inserted and rotating, the connector can eliminate small discrepancies in real average power. c. Calibration differences between the oscilloscope in the test setup and the oscilloscope used to measure the sample optical eye diagram can cause small discrepancies in measured average power. Confirm that the extinction ratio is close to the value reported in the sample optical eye diagram. If the value is significantly different, this indicates that there is a problem with the test setup, evaluation board, or TOSA and this should be investigated. Because the extinction ratio is a sensitive measurement, small discrepancies can be attributed to using different oscilloscope or optical plug-in models or even different optical plug-ins of the same model. Select the same eye mask and mask Y-alignment method as used in the sample optical eye diagram. Select the same number of waveforms for the eye diagram capture as used in the sample optical eye diagram. Confirm that the average mask margin is close to the value reported in the sample optical eye diagram. If the value is significantly different, this indicates that there is a problem with the test setup, evaluation board, or TOSA and this should be investigated. Differences can be attributed to one or more of the following: a. A poor quality differential electrical eye diagram at the output of the coaxial cables from the pattern generator results in a poor optical eye diagram. Measuring the electrical eye diagram on these signals confirms or eliminates this possibility. Delay skew >2 ps between the DATAP and DATAN signals is one example of a degraded input signal that leads to a degraded optical eye diagram. b. Small discrepancies can be attributed to using different oscilloscope or optical plug-in models or even different optical plug-ins of the same model. Different optical plug-in models have different bandwidths, noise, and time-base jitter and this can affect eye mask margin. Different optical plug-ins of the same model can have different frequency responses in the optical filter that is within the allowed tolerance and this can affect eye mask margin. c. If an optical attenuator is required to keep the eye diagram within the oscilloscope range, an attenuation value should be chosen that keeps the optical signal in the upper end of the oscilloscope range. Otherwise, the effect of oscilloscope noise on the eye mask margin is increased. EVAL-ADN2525-NT/ADN2525-OP affect the high frequency performance in ways that are difficult to predict; therefore, changing them increases the risk of losing some mask margin performance. Following this recommendation gives the highest likelihood that eye diagram performance measured on the evaluation board is reproduced in the optical transmitter (ignoring any performance loss contributed by retiming or other circuitry that precedes the ADN2525). It is possible that changing the PCB dielectric material or making small changes to the PCB layout causes negligible degradation in the performance or even improves the performance. However, this is difficult to predict. USING THE EVALUATION BOARD PCB LAYOUT IN AN OPTICAL TRANSMITTER DESIGN The evaluation kit PCB is fabricated using FR4 (Polyclad PCLFR-370HR) with 4.5 mil dielectric thickness between the topside signal and ground layers. When using the evaluation board PCB layout as a guide for designing an optical transmitter, it is recommended that the same dielectric material and thickness be used and the PCB layout associated with the ADN2525, the ac-coupling components, and the TOSA be copied exactly. This includes features such as component pad positions and sizes, track widths and lengths, via sizes, and positions. These features 1.059 0.27 0.6 0.098 2.974 2.82 2.606 2.276 1.496 2.106 1.776 THERMISTOR 3.128 CASE GND LD ANODE LD CATHODE CASE GND MPD CATHODE 0.506 0.886 0.176 0 0.155 0.6 NOTES 1. DIMENSIONS SHOWN IN INCHES. 0.095 Figure 3. Evaluation Board Outline Rev. 0 | Page 5 of 8 0.87 0.964 06368-010 0.27 0 EVAL-ADN2525-NT/ADN2525-OP EVALUATION BOARD SCHEMATICS AND ARTWORK GND TP1 R12 GND SMA TP2 VCC C12 GND VCC GND C10 VCC Z0 = 50Ω T6 ROS J6 GND ROS J5 GND BSET IBMON IBIAS VCC Z0 = 50Ω T9 C5 GND Z0 = 50Ω T7 R2 3 × 3 LFCSP Z0 = 50Ω T8 VCC C11 C3 EXPOSED PAD TO GND DATAN VCC MSET Z0 = 25Ω L6 T1 C15 L1 L5 GND GND C14 4 IMODN VCC NC R10 IMODP ADN2525 GND C6 VCC U3 DATAP L2 GND ALS Z0 = 25Ω VCC T2 L7 L8 L4 R11 L3 A B 1 P4 C13 J1 SMA GND SMA GND GND VCC C2 GND J3 GND R9 LD_ANODE GND THERMISTOR TOSA TP4 VCC GND VCC C1 Z0 = 25Ω 5 GND T4 6 GND GND SMA J4 GND VCC TP5 GND R1 R8 1 PD_CATHODE 2 Z0 = 25Ω GND GND T3 3 LD_CATHODE Z0 = 25Ω T5 SMA J9 R30 GND 06368-003 J2 R3 NC = NO CONNECT 06368-004 06368-005 Figure 4. Schematic of Generation F Evaluation Board Figure 6. Layer 2 (GND) Figure 5. Layer 1 (Signal) Rev. 0 | Page 6 of 8 06368-007 06368-006 EVAL-ADN2525-NT/ADN2525-OP Figure 9. Silkscreen Top 06368-009 06368-008 Figure 7. Layer 3 (VCC) Figure 8. Layer 4 (Signal) Figure 10. Silkscreen Bottom (Bottom View) Rev. 0 | Page 7 of 8 EVAL-ADN2525-NT/ADN2525-OP ORDERING INFORMATION BILL OF MATERIALS Table 4. Qty 2 2 2 2 4 3 2 2 4 1 1 1 1 1 1 2 4 1 1 Reference Designator R1, R3 R10, R11 R8, R9 C14, C15 C10, C11, C12, C13 C1, C5, C6 L6, L8 L5, L7 L1, L2, L3, L4 R2 C3 C2 P4 R12 R30 J5, J6 J1, J2, J3, J4 U3 TOSA (EVAL-ADN2525-OP only) Description 0 Ω, 0402 size resistor 10 Ω, 0603 size resistor 100 Ω, 0603 size resistor 1000 nF, 0402 size capacitor; 100 nF, 0402 size ceramic capacitor; 10 nF, 0402 size ceramic capacitor; 18 nH, 0402 size inductor; 0402 size ferrite 10 μH, 0805 size inductor 33 Ω, 0201 size resistor; mounted upside-down 0.1 pF, 0201 size capacitor 10 μF, Case-C tantalum capacitor Jumper and 3-pin header 1 kΩ, 0603 size, 0.1% resistor 25 Ω, not populated 2.92 mm connector Side-launch SMA connector 10.7 Gbps differential laser diode driver 10 Gbps XMD TOSA Supplier/Number Panasonic ECJ-0EB0J105K BC Components VJ0402V104ZXJCW1BC BC Components VJ0402Y103KXJCW1BC Murata LQW15AN20NJ0 Murata BLM15HG102SN1 Murata LQM21FN100M70L Panasonic ERJ-1GEF330C AVX 02013J0R1PBWTR Rosenberger Analog Devices ADN2525 OpNext LD5033SMDL ORDERING GUIDE Model EVAL-ADN2525-OPZ 1 EVAL-ADN2525-NTZ1 1 Description Optical Evaluation Board with an XMD TOSA Populated Optical Evaluation Board Without an XMD TOSA Populated Z = RoHS Compliant Part. ESD CAUTION ©2007 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. EB06368-0-7/07(0) Rev. 0 | Page 8 of 8