10.7 Gbps, 3.3 V, Low Noise, TIA with Average Power Monitor ADN2820 FEATURES PRODUCT DESCRIPTION Technology: high performance SiGe Bandwidth: 9 GHz Input noise current density: 1.0 A Optical sensitivity: -19.3 dBm Differential transimpedance: 5000 V/A Power dissipation: 200 mW Input current overload: 2.8 mA p-p Linear input range: 0.15 mA p-p Output resistance: 50 /side Output offset adjustment range: 240 mV Average input power monitor: 1 V/mA Die size: 0.87 mm x 1.06 mm The ADN2820 is a compact, high performance, 3.3 V power supply SiGe transimpedance amplifier (TIA) optimized for 10 Gbps Metro-Access and Ethernet systems. It is a single chip solution for detecting photodiode current with a differential output voltage. The ADN2820 features low input referred noise current and high output transimpedance gain, capable of driving a typical CDR or transceiver directly. A POWMON output is provided for input average power monitoring and alarm generation. Low nominal output offset enables dc output coupling to 3.3 V circuits. The OFFSET control input enables output slice level adjustment for asymmetric input signals. The ADN2820 operates with a 3.3 V power supply and is available in die form. APPLICATIONS 10.7 Gbps optical modules SONET/SDH OC-192/STM-64 and 10 GbE receivers, transceivers, and transponders FUNCTIONAL BLOCK DIAGRAM 3.3V VCC (1,2,3) RF 50 50 RF = 500 OUT (5) OUTB (6) h OFFSET (14) AV = 20dB IN (13)' CB 0.85V 20mA CF POWMON (8) GND (10, 11) GND (4,7) CLF (9) CLF 03194-0-001 Figure 1. Functional Block Diagram/Typical Operating Circuit Rev. 0 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. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices. Trademarks and registered trademarks are the property of their respective owners. One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A. Tel: 781.329.4700 www.analog.com Fax: 781.326.8703 (c) 2003 Analog Devices, Inc. All rights reserved. ADN2820 TABLE OF CONTENTS Specifications..................................................................................... 3 Applications........................................................................................8 Absolute Maximum Ratings............................................................ 4 Optical Sensitivity .........................................................................8 ESD Caution.................................................................................. 4 Optical Power Monitor.................................................................8 Pad Layout and Functional Descriptions ...................................... 5 Output Offset Adjust Input ..........................................................9 Pad Layout ..................................................................................... 5 Low Frequency Transimpedance Cutoff Capacitor Selection.9 Die Information............................................................................ 5 Bandwidth versus Input Bond Wire Inductance.................... 10 Pad Descriptions........................................................................... 5 Bandwidth versus Output Bond Wire Inductance................. 10 Pad Coordinates ........................................................................... 5 Butterfly Package Assembly ...................................................... 11 Typical Performance Characteristics ............................................. 6 Outline Dimensions ....................................................................... 12 Ordering Guide .......................................................................... 12 REVISION HISTORY Revision 0: Initial Version Rev. 0 | Page 2 of 12 ADN2820 SPECIFICATIONS Table 1. Electrical Specifications Parameter DYNAMIC PERFORMANCE Bandwidth1, 2 Total Input RMS Noise1, 2 Small Signal Transimpedance Transimpedance Ripple Group Delay Variation 2 2 Total Peak-to-Peak Jitter 2, 3 Low Frequency Cutoff S22 Linear Input Range Input Overload Current1, 2 Maximum Output Swing DC PERFORMANCE Power Dissipation Input Voltage Output Common-Mode Voltage Output Offset Offset Adjust Sensitivity Offset Adjust Range POWMON Sensitivity POWMON Offset Conditions1 Min Typ -3 dB DC to 10 GHz 100 MHz 100 MHz to 3 GHz 100 MHz to 3 GHz 100 MHz to 9 GHz IIN,P-P = 2.5 mA CLF = 0.1 F DC - 10 GHz, differential Peak-to-peak, <1 dB compression ER = 10 dB ER = 4 dB Differential, IIN P-P = 2.0 mA 7.5 9 1.0 5000 0.5 10 30 17 12 -10 0.15 2.8 1.9 1.1 4000 1.4 1.0 0.88 147 0.75 DC terminated to VCC IIN, AVE < 0.1 mA See Figure 3 See Figure 3 IIN, AVE = 10 A to 1 mA IIN, AVE = 0 A -20 0.76 200 0.85 VCC - 0.3 3 120 240 1 20 Max 6000 264 0.93 +20 1.2 Unit GHz A V/A dB ps ps ps kHz dB mA mA p-p mA p-p V p-p mW V V mV mV/V mV V/mA mV Min/Max VCC = 3.3 V 0.3 V, TAMBIENT = -15C to +85C; Typ VCC = 3.3 V, TAMBIENT = 25C. Photodiode capacitance CD = 0.22 pF 0.04 pF; photodiode resistance = 20 ; CB = CF = 100 pF; RF = 100 ; input wire bond inductance LIN = 0.5 nH 0.15 nH; output bond wire inductance LOUT, OUTB = 0.85 nH 0.15 nH; load impedance = 50 (each output, dc- or ac-coupled). 3 10-12 BER, 8 dB extinction ratio, 0.85 A/W PIN responsivity. 1 2 Rev. 0 | Page 3 of 12 ADN2820 ABSOLUTE MAXIMUM RATINGS Table 2. ADN2820 Absolute Maximum Ratings Parameter Supply Voltage (VCC to GND) Internal Power Dissipation Output Short Circuit Duration Maximum Input Current Storage Temperature Range Operating Ambient Temperature Range Maximum Junction Temperature Die Attach Temperature (<60 seconds) Rating 5.2 V Indefinite 5 mA -65C to +125C -15C to +85C 165C 450C Stresses above those listed under Absolute Maximum Ratings may cause permanent damage to the device. This is a stress rating only; functional operation of the device at these or any other conditions above those indicated in the operational section of this specification is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ESD CAUTION ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the human body and test equipment and can discharge without detection. Although this product features proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance degradation or loss of functionality. Rev. 0 | Page 4 of 12 ADN2820 PAD LAYOUT AND FUNCTIONAL DESCRIPTIONS PAD LAYOUT DIE INFORMATION Die Size 14 1 2 3 VCC VCC VCC GND OFFSET 0.875 mm x 1.060 mm 4 Die Thickness 12 mils = 0.3 mm Passivation Openings 13 OUT 5 OUTB 6 IN 0,0' 0.08 mm x 0.08 mm 0.12 mm x 0.08 mm 12 TEST 0.08 mm x 0.12 mm 11 GND GND GND CLF POWMON 10 9 8 7 Passivation Composition 5000 A Si3N4 (Top) +5000 A SiO2 (Bottom) 03194-0-002 Pad Composition Al/1% Cu Figure 2. ADN2820 Pad Layout Backside Contact P-Type Handle (Oxide Isolated from Active Circuitry) PAD DESCRIPTIONS Table 3. Pad Descriptions Pin No. 1-3 4, 7, 10, 11 5 6 8 Pad VCC GND OUT OUTB POWMON 9 12 13 CLF TEST IN 14 OFFSET Function Positive Supply. Bypass to GND with a 100 pF or greater single-layer capacitor. Ground. Positive Output. Drives 50 termination (ac or dc termination). Negative Output. Drives 50 termination (ac or dc termination). Input Average Power Monitor. Analog signal proportional to average optical input power. Leave open if unused. Low Frequency Cutoff Setpoint. Connect with a 0.1 F capacitor to GND for 20 kHz. Test Pad. Leave Floating. Current Input. Bond directly to reverse biased PIN or APD anode. Filter PIN or APD anode with 100 pF x 100 or greater. Output Offset Adjust Input. Leave open if not being used and the input slice threshold will automatically be set to the eye center. PAD COORDINATES Table 4. Pad Coordinates Pin No. 1 2 3 4 5 6 7 PAD VCC VCC VCC GND OUT OUTB GND X (mm) -0.20 0.00 0.20 0.35 0.35 0.35 0.35 Y (mm) 0.45 0.45 0.45 0.30 0.10 -0.10 -0.30 Pin No. 8 9 10 11 12 13 14 Rev. 0 | Page 5 of 12 PAD POWMON CLF GND GND TEST IN OFFSET X (mm) 0.20 0.00 -0.20 -0.35 -0.35 -0.35 -0.35 Y (mm) -0.45 -0.45 -0.45 -0.30 -0.10 0.10 0.30 ADN2820 TYPICAL PERFORMANCE CHARACTERISTICS 0.25 -10 0.20 -15 -20 0.10 0.05 |s22| (dB) VOUT DIFFERENTIAL (V) 0.15 0 -0.05 -25 -30 -35 -0.10 -40 -0.15 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 3.3 OFFSET CONTROL INPUT (V) -50 0.01 03194-0-008 -0.25 Figure 3. VOUT Differential vs. OFFSET Adjust 1 Figure 6. Differential S22 vs. Frequency 10 VPOWMON (V) 0.001 1 10 100 1k 10k IIN (A) 800 600 400 200 0 03194-0-009 0.1 1000 0 LOG 5dB/REF 0dB 2:11.571dB 1.0 1.5 2.0 2.5 3.0 INPUT CURRENT (mA p-p) Figure 4. VPOWMON vs. IIN S21 0.5 03194-0-012 DIFFERENTIAL OUTPUT VOLTAGE (mV p-p) 1200 1 Figure 7. Output Voltage vs. Input Current 8.156 326 057GHz 80 CH1 MARKERS 1:14.563 dB 100.000 MHz 75 1 TZ GAIN (dB ) 2 70 65 60 START .050 000 000GHz STOP 20.000 000 000GHz 50 0 0.5 1.0 1.5 2.0 2.5 INPUT CURRENT (mA p-p) Figure 8. Transimpedance Gain vs. Input Current Figure 5. ADN2820 S21 Rev. 0 | Page 6 of 12 3.0 03194-0-013 55 03194-0-010 CH1 0.1 FREQUENCY (GHz) 03194-0-011 -45 -0.20 ADN2820 40 TOTAL JITTER p-p (ps) 35 30 25 20 15 10 0 0.5 1.0 1.5 2.0 2.5 3.0 AVERAGE CURRENT (mA) Figure 9. Total Jitter Peak-to-Peak vs. Average Input Current (IIN = 2 mA p-p) 03194-0-016 0 03194-0-014 5 Figure 11. Electrical Eye Diagram at 10 Gbps, PRBS 2 31 with IIN = 100 A p-p 60 40 30 20 0 0 0.5 1.0 1.5 2.0 2.5 3.0 INPUT AMPLITUDE p-p (mA) Figure 10. Total Jitter Peak-to-Peak vs. Input Amplitude (ER = 10 dB) 03194-0-017 10 03194-0-015 TOTAL JITTER p-p (ps) 50 Figure 12. Electrical Eye Diagram at 10 Gbps, PRBS 2 31 with IIN = 2.5 mA p-p Rev. 0 | Page 7 of 12 ADN2820 APPLICATIONS OPTICAL SENSITIVITY (IRMS x + VS / ZT ) x (ER + 1) x (1000mW /W ) 2( ER - 1) where: = photodiode responsivity (A/W), 0.85 A/W typical IRMS = TIA input referred noise (A), typically 1.05 A for the ADN2820 = BER factor, = 14.1 for 10-12 BER ER = extinction ratio, 8 dB typical VS = PA/CDR input sensitivity (V), 5 mV to 100 mV ZT = TIA transimpedance (V/A), 5 k for ADN2820 OPM (W) = (POWMON (V) - POWMONOFFSET (V))/( (A/W) x POWMONGAIN (V/A)) OPM calculation from typical ADN2820 POWMON versus IIN,AVE measurement data: (POWMONOFFSET = 20 mV, POWMONGAIN = 1 V/mA, =1 A/W) 0 -5 Table 5. Optical Sensitivity -15 -20 -25 -30 -30 OPTICAL POWER MONITOR -25 -20 -15 -10 -5 0 AVERAGE INPUT POWER (dBm) Average optical power monitor (OPM) measurement is a recommended diagnostic feature in module multisource specification agreements (MSAs) such as the 300-pin 10 Gb transponder (MSA300) and 10 Gb form factor pluggable module (XFP) specifications. 03194-0-001 10 mV 5 mV OPM (dBm) Optical Input Sensitivity (dBm) PA/CDR 100 mV Input 50 mV Sensitivity (VS) 25 mV -10 Transimpedance (ZT) 2 k 5 k Infinite -13.1 -15.7 -19.3 -15.1 -17.1 -19.3 -16.7 -18.1 -19.3 -18.1 -18.8 -19.3 -18.7 -19.0 -19.3 Figure 13. POWMON Transfer Function The ADN2820 enables the simple calculation of OPM using the POWMON output, which is linearly proportional to the average input current. When monitoring the POWMON output, connect to a high impedance input; typical POWMON output impedance is 1 k. To disable the POWMON feature, leave the pad floating (not bonded). Assuming linear diode responsivity , average input current is linearly proportional to average input power: OPM MEASUREMENT ERROR (dB) 1.0 0.6 0.2 -0.2 -0.6 -1.0 -30 IIN,AVE (A) = (A/W) x PIN,AVE (W) -25 -20 -15 -10 AVERAGE INPUT POWER (dBm) Ideally, Figure 14. POWMON Accuracy POWMON (V) = (A/W) x PIN,AVE (W) x POWMONGAIN (V/A) + POWMONOFFSET (V) Rev. 0 | Page 8 of 12 -5 0 03194-0-002 Sensitivity(dBm) = 10 log 10 From a POWMON measurement, the average input power can be estimated by calculating the optical power monitor (OPM): ADN2820 OUTPUT OFFSET ADJUST INPUT Long reach optical links may suffer from unbalanced 1 and 0 signal shaping due to dispersion and/or optical or avalanche amplification noise. The ADN2820 enables the user to adjust the input-referred slice level by adjusting the output offset with the ADN2820's outputs dc-coupled. With the OFFSET pad open (not bonded), the average output voltage offset [OUT - OUTB] is internally balanced to be less than 5 mV. When externally driven by a voltage source, the ADN2820 average output voltage offset [OUT - OUTB] is linearly proportional to an applied OFFSET input voltage: Digital encoding methods may generate long strings of 1s or 0s, requiring the transimpedance amplifier pass band to extend to 1 MHz or below. To accommodate this requirement, the ADN2820 has -3 dB low frequency transimpedance cutoff set by external capacitor CLF. For CLF, values greater than 1000 pF, the typical -3 dB low frequency transimpedance cutoff can be estimated by the equation f-3dB ~ 2 kHz x (1 F/CLF) Because CLF is not part of the 10 Gbps signal chain, it is not required to be a high frequency capacitor type. A ceramic capacitor is recommended. Applied Offset (V) = (OFFSET (V) - ~1.6 V) x OFFSETGAIN (mV/V) where: With transimpedance, TZ, the input referred slice adjust can be calculated from the following equation: Input Slice Adjust = 1/TZ x (OFFSET (V) - ~1.6 V) x OFFSETGAIN (mV/V)) 50 40 30 20 10M 1M 100k 10k 1k 1pF 10 10pF 0.1nF 1nF 10nF 0.1F EXTERNAL CLF CAPACITANCE VALUE 1F 03194-0-004 OFFSETGAIN = 120 mV/V TZ -3dB LOW FREQUENCY CUTOFF (Hz) 100M OFFSET = voltage applied to the OFFSET pad 0 Figure 16. Low Frequency Transimpedance Cutoff vs. CLF Capacitance Using Typical Data with a 0.1 F Ceramic Capacitor and Simulation Results with 1 pF to 1 F Capacitance -10 -20 -30 -40 -50 0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 OFFSET CONTROL INPUT (V) 03194-0-003 INPUT REFERRED SLICE ADJUST (A) LOW FREQUENCY TRANSIMPEDANCE CUTOFF CAPACITOR SELECTION Figure 15. Input Slice Adjust vs. OFFSET Calculation Using Typical [OUT,OUTB] vs. OFFSET Measurement Data Rev. 0 | Page 9 of 12 ADN2820 BANDWIDTH VERSUS INPUT BOND WIRE INDUCTANCE BANDWIDTH VERSUS OUTPUT BOND WIRE INDUCTANCE The ADN2820's -3 dB bandwidth (BW) is a strong function of input (IN) bond wire inductance (LIN). The maximum BW peaks near and falls rapidly after the resonant frequency of the input bond wire inductance and photodiode capacitance (CD) ~ 1/(2 x (LIN x CD)). The ADN2820 -3 dB bandwidth (BW) depends strongly on the output (OUT, OUTB) inductance values (LOUT, LOUTB). With output inductance greater than 2 nH, the BW is dominated by the output LOUT, LOUTB/(RO + RL) settling time constant, where RO = RL = 50 are the nominal single-ended output resistance and load impedance. Table 6. Simulated ADN2820 -3 dB BW vs. LIN Table 7. Simulated ADN2820 -3 dB BW vs LOUT, LOUTB LIN (nH) 0 1 2 3 LOUT, LOUTB (nH) 0 1 2 3 -3 dB Bandwidth (GHz) 7.4 9.0 7.8 7.0 76 3nH 75 76 2nH 1nH 75 0nH 74 1nH SIMULATED DIFFERENTIAL TRANSIMPEDANCE (dB ) 73 0nH 72 71 70 69 68 67 73 72 3nH 2nH 71 70 69 68 67 10 FREQUENCY (GHz) 100 Figure 17. Simulated Differential Transimpedance (dB) vs. Frequency (Hz) with 0 nH, 1 nH, 2 nH, and 3 nH LIN Inductance Note: LOUT, LOUTB = 1 nH, CD = 0.22 pF. Recommendation: LIN x CD = 1 nH x 0.22 pF. 66 0.1 03194-0-005 1 1 10 FREQUENCY (GHz) 100 03194-0-006 SIMULATED DIFFERENTIAL TRANSIMPEDANCE (dB ) 74 66 0.1 -3 dB Bandwidth (GHz) 9.1 9.0 7.5 5.9 Figure 18. Simulated Differential Transimpedance (dB) vs. Frequency (Hz) with 0 nH, 1 nH, 2 nH, and 3 nH LOUT, LOUTB inductance Note: LIN = 1 nH, CD = 0.22 pF. Recommendation: LOUT, LOUTB 1 nH Rev. 0 | Page 10 of 12 ADN2820 BUTTERFLY PACKAGE ASSEMBLY OFFSET VCC 7.5mm Rf Cb 5mm Cf OUT OUTB PD 2.5mm Clf POWMON 03194-0-007 0mm Figure 19. Butterfly Package Table 8. Bill of Materials PD TIA CB CLF CF RF Qty. 1 1 2 1 1 1 Description VENDOR SPECIFIC (0.5 mm x 0.5 mm) ADN2820 (0.87 mm x 1.06 mm) GM250X7R10216 (0.5 mm x 0.5 mm) GM260Y5V104Z10 (0.8 mm x 0.8 mm) D20BV201J5PX (0.5 mm x 0.5 mm) WMIF0021000AJ (0.4 mm x 0.5 mm) Source 10 Gbps Photodiode Analog Devices SiGe 10 Gbps Transimpedance Amplifier Murata 1000 pF Ceramic Single Layer Capacitor Murata 0.1 F Ceramic Single Layer Capacitor DiLabs 100 pF RF Single Layer Capacitor Vishay 100 Thin Film Microwave Resistor Rev. 0 | Page 11 of 12 ADN2820 OUTLINE DIMENSIONS 1 2 3 4 14 13 5 ADN2820 1.060 mm SINGLE PAD SIZE: 0.080 mm x 0.080 mm (pads 1, 2, 3, 5, 6, 8, 9, 12, 13, 14) 6 12 DOUBLE PAD SIZE: 0.120 mm x 0.080 mm (pads 4, 7, 10, 11) 11 7 9 10 8 0.875 mm 0.30 mm Figure 20. 14-Pad Bare Die Dimensions shown in millimeters ORDERING GUIDE Model ADN2820ACHIPS Temperature Range -25C to +85C (c) 2003 Analog Devices, Inc. All rights reserved. Trademarks and registered trademarks are the property of their respective owners. C03194-0-10/03(0) Rev. 0 | Page 12 of 12 Package Description Die Form