ONET4291TAY

ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 4.25-Gbps Transimpedance Amplifier With AGC and RSSI FEATURES APPLICATIONS • • • • • • • • • • • 2.8-GHz Bandwidth 3.2-kΩ Differential Transimpedance Automatic Gain Control (AGC) 8.8-pA/√Hz Typical Input Referred Noise 2-mAp-p Maximum Input Current Received Signal Strength Indication (RSSI) CML Data Outputs With On-Chip 50-Ω Back-Termination On-Chip Supply Filter Capacitor Single 3.3-V Supply Die Size: 0,78 × 1,18 mm • • • SONET/SDH Transmission Systems at OC24 and OC48 4.25-Gbps, 2.125-Gbps, and 1.0625-Gbps Fiber-Channel Receivers Gigabit Ethernet Receivers PIN Preamplifier-Receivers DESCRIPTION The ONET4291TA is a high-speed transimpedance amplifier used in optical receivers with data rates up to 4.25 Gbps. It features a low input referred noise, 2.8-GHz bandwidth, automatic gain control (AGC), 3.2-kΩ transimpedance, and received signal strength indication (RSSI). The ONET4291TA is available in die form and is optimized for use in a TO can. The ONET4291TA requires a single 3.3-V supply, and its power-efficient design typically dissipates less than 56 mW. The device is characterized for operation from –40°C to 85°C ambient temperature. AVAILABLE OPTIONS TA DIE –40°C to 85°C ONET4291TAY Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2005, Texas Instruments Incorporated ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 BLOCK DIAGRAM The ONET4291TA is a high-performance, 4.25-Gbps transimpedance amplifier consisting of the signal path, supply filter, a control block for dc input current cancellation, automatic gain control (AGC), received signal strength indication (RSSI), and a band-gap voltage reference and bias current generation block. The signal path comprises a transimpedance amplifier stage, a voltage amplifier, and a CML output buffer. The on-chip filter circuit provides filtered VCC for the photodiode and for the transimpedance amplifier. The dc input current cancellation and AGC use internal low-pass filters to cancel the dc current on the input and to adjust the transimpedance amplifier gain. Furthermore, circuitry to monitor the received signal strength is provided. A simplified block diagram of the ONET4291TA is shown in Figure 1. VCC 275 pF GND 220 W Band-Gap Voltage Reference and Bias Current Generation 200 pF FILTER DC Input Current Cancellation, AGC, and RSSI RSSI RF OUT+ IN OUT– Transimpedance Amplifier Voltage Amplifier CML Output Buffer B0066-01 Figure 1. Simplified Block Diagram of the ONET4291TA SIGNAL PATH The first stage of the signal path is a transimpedance amplifier that takes the photodiode current and converts it into a voltage signal. If the input signal current exceeds a certain value, the transimpedance gain is reduced by means of AGC circuitry. The second stage is a voltage amplifier that provides additional gain and converts its single-ended input voltage into a differential data signal. The third signal-path stage is the output buffer, which provides CML outputs with on-chip, 50-Ω back-termination to VCC. 2 Submit Documentation Feedback ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 FILTER CIRCUITRY The filter pin provides filtered VCC for the photodiode bias. The on-chip, low-pass filter for the photodiode VCC is implemented using a filter resistor of 220 Ω and an internal 200-pF capacitor. The corresponding corner frequency is below 4 MHz. The supply voltage for the whole amplifier is filtered by means of an on-chip, 275-pF capacitor as well, thus avoiding the necessity to use an external supply-filter capacitor. DC INPUT CURRENT CANCELLATION, AGC, AND RSSI The voltage drop across the internal photodiode supply-filter resistor is monitored by means of a dc input current cancellation, AGC, and RSSI control circuit block. If the dc input current exceeds a certain level, it is partially cancelled by means of a controlled current source. This measure keeps the transimpedance amplifier stage within sufficient operating point limits for optimum performance. Furthermore, disabling the dc input cancellation at low input currents leads to superior noise performance. The AGC circuitry lowers the effective transimpedance feedback resistor RF by means of a MOSFET device acting as a controlled shunt. This prevents the transimpedance amplifier from being overdriven at high input currents, which leads to improved jitter behavior within the complete input-current dynamic range. Because the voltage drop across the supply-filter resistor is sensed and used by the AGC circuit, the photodiode must be connected to a FILTER pad for the AGC to function correctly. Finally, this circuit block senses the current through the filter resistor and generates a mirrored current, which is proportional to the input signal strength. The mirrored current is available at the RSSI output and must be sunk to ground (GND) using an external resistor. The RSSI gain can be adjusted by choosing the external resistor; however, for proper operation, ensure that the voltage at the RSSI pad never exceeds VCC – 0.65 V. BAND-GAP VOLTAGE AND BIAS GENERATION The ONET4291TA transimpedance amplifier is supplied by a single, 3.3-V supply voltage connected to the VCC pad. This voltage is referred to GND. On-chip band-gap voltage circuitry generates a supply-voltage-independent reference from which all other internally required voltages and bias currents are derived. Submit Documentation Feedback 3 ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 BOND PAD ASSIGNMENT The ONET4291TA is available as a bare die. The locations of the bond pads are shown in the following figure. 1 10 GND GND 2 9 GND OUT+ 3 8 OUT– VCC 4 7 RSSI 6 IN FILTER 5 4291TAA GND M0033-04 BOND PAD DESCRIPTION PAD TYPE DESCRIPTION 5 Analog Bias voltage for photodiode (cathode). This pads connects through an internal 220-Ω resistor to VCC and a 200-pF filter capacitor to ground (GND). The FILTER pad(s) must be connected to the photodiode for the AGC to function. 1, 2, 9, 10 Supply Circuit ground. All GND pads are connected on die. Bonding all pads is optional; however, for optimum performance a good ground connection is mandatory. IN 6 Analog input OUT+ 3 Analog output Non-inverted data output. On-chip 50-Ω back-terminated to VCC. OUT– 8 Analog output Inverted data output. On-chip 50-Ω back-terminated to VCC. Analog output current proportional to the input data amplitude. Indicates the strength of the received signal (RSSI). Must be sunk through an external resistor to ground (GND). The RSSI gain can be adjusted by choosing the external resistor; however, for proper operation, ensure that the voltage at the RSSI pad never exceeds VCC – 0.65 V. If the RSSI feature is not used, this pad must be bonded to ground (GND) to ensure proper operation. NAME NO. FILTER GND RSSI 7 Analog output VCC 4 Supply 4 Data input to TIA (photodiode anode) 3.3-V, +10%/–12% supply voltage Submit Documentation Feedback ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 ABSOLUTE MAXIMUM RATINGS over operating free-air temperature range (unless otherwise noted) (2) VCC Supply voltage VFILTER, VOUT+, VOUT–, VRSSI Voltage at FILTER, OUT+, OUT–, RSSI IIN Current into IN IFILTER Current into FILTER IOUT+, IOUT– Continuous current at outputs ESD (1) –0.3 V to 4 V –0.3 V to 4 V –0.7 mA to 2.5 mA – 8 mA to 8 mA ESD rating at all pins except IN ESD rating at IN (2) – 8 mA to 8 mA (3) 1.5 kV (HBM) (3) 300 V (HBM) TJ,max Maximum junction temperature Tstg Storage temperature range –65°C to 85°C TA Operating free-air temperature range –40°C to 85°C (1) (2) (3) 125°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 under "recommended operating conditions" is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltage values are with respect to network ground terminal. For optimum high-frequency performance, the input pin has reduced ESD protection. RECOMMENDED OPERATING CONDITIONS over operating free-air temperature range (unless otherwise noted) MIN NOM MAX VCC Supply voltage 2.9 3.3 3.6 TA Operating free-air temperature –40 LFILTER, LIN Wire-bond inductor at pins FILTER and IN CPD Photodiode capacitance UNIT V 85 °C 0.8 nH 0.2 pF DC ELECTRICAL CHARACTERISTICS over recommended operating conditions (unless otherwise noted). Typical values are at VCC = 3.3 V and TA = 25°C. PARAMETER VCC TEST CONDITIONS Supply voltage IVCC Supply current VIN Input bias voltage ROUT Output resistance RFILTER Photodiode filter resistance Average photodiode current IPD = 0 mA Single-ended to VCC MIN TYP MAX 2.9 3.3 3.6 11 17 25 0.85 1.05 V 50 60 Ω 40 220 Submit Documentation Feedback UNIT V mA Ω 5 ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 AC ELECTRICAL CHARACTERISTICS over recommended operating conditions (unless otherwise noted). Typical values are at VCC = 3.3 V and TA = 25°C. PARAMETER iIN-OVL AC input overload current ARSSI RSSI gain TEST CONDITIONS MIN Resistive load to GND (1) Small-signal transimpedance Differential output; input current iIN = 50 µAp-p fH,3dB Small-signal bandwidth iIN = 50 µAp-p (2) fL,3dB Low-frequency, –3-dB bandwidth – 3 dB, input current iIN < 50 µAp-p fH,3dB,RSSI RSSI bandwidth iN-IN Input referred RMS noise 1 2300 2.2 2.8 (3) (2) (3) (4) 6 30 µA 3900 Ω 465 (4) iIN = 100 µAp-p (K28.5 pattern) (4) iIN = 1 mAp-p (K28.5 pattern) iIN = 2 mAp-p (K28.5 pattern) (1) 15 3200 GHz 70 Input current iIN = 1 mAp-p 140 kHz MHz 590 8.8 iIN = 50 µAp-p (K28.5 pattern) VOUT,D,MAX Maximum differential output voltage A/A 3.5 50 kHz–4 GHz UNIT 1.05 40 Input referred noise current density Deterministic jitter MAX mAp-p 0.95 RSSI output offset current (no light) Z21 DJ TYP 2 nA pA/√Hz 10 23 10 30 8 28 13 42 200 310 psp-p mVp-p The RSSI output is a current output, which requires a resistive load to ground (GND). The voltage gain can be adjusted for the intended application by choosing the external resistor. However, for proper operation of the ONET4291TA, ensure that the voltage at RSSI never exceeds VCC – 0.65 V. The minimum small-signal bandwidth is specified over process corners, temperature, and supply voltage variation. The assumed photodiode capacitance is 0.2 pF. The bond-wire inductance is 0.8 nH. The small-signal bandwidth strongly depends on environmental parasitics. Careful attention to layout parasitics and external components is necessary to achieve optimal performance. Input referred RMS noise is (RMS output noise)/(gain @ 100 MHz). The maximum input referred noise is specified over process corners, temperature, and supply voltage variation. At small input currents a significant portion of the deterministic jitter (DJ) is caused by duty-cycle distortion (DCD) due to residual offset in the output signal. Because the TIA is not limiting, the DCD portion of the DJ is removed by the following limiting amplifier. The given maximum values include DCD as well as six-sigma margin. Submit Documentation Feedback ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 TYPICAL CHARACTERISTICS Typical operating condition is at VCC = 3.3 V and TA = 25°C. UNFILTERER INPUT REFERRED NOISE vs AVERAGE INPUT CURRENT UNFILTERED INPUT REFERRED NOISE vs AMBIENT TEMPERATURE 800 2400 Input Referred Noise Current − nARMS Input Referred Noise Current − nARMS 2200 2000 1800 1600 1400 1200 1000 800 600 400 700 600 500 400 300 200 100 200 0 10 100 Average Input Current − µA TA − Ambient Temperature − °C G001 Figure 2. Figure 3. SMALL-SIGNAL TRANSIMPEDANCE vs AMBIENT TEMPERATURE TRANSIMPEDANCE vs AVERAGE INPUT CURRENT 5000 4000 4500 3500 4000 3000 Transimpedance − Ω Transimpedance − Ω 0 −40 −30 −20 −10 0 10 20 30 40 50 60 70 80 90 1k 3500 3000 2500 2500 2000 1500 2000 1000 1500 500 1000 −40 −30 −20 −10 0 10 20 30 40 50 60 70 80 90 TA − Ambient Temperature − °C G002 0 0 100 200 300 400 500 600 700 800 900 1000 Average Input Current − µA G003 Figure 4. G004 Figure 5. Submit Documentation Feedback 7 ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 TYPICAL CHARACTERISTICS (continued) Typical operating condition is at VCC = 3.3 V and TA = 25°C. SMALL-SIGNAL BANDWIDTH vs AMBIENT TEMPERATURE SMALL-SIGNAL TRANSFER CHARACTERISTICS 70 3.00 2.95 68 Transimpedance − dBΩ 2.90 Bandwidth − GHz 2.85 2.80 2.75 2.70 2.65 66 64 62 60 2.60 58 2.55 2.50 −40 −30 −20 −10 0 10 20 30 40 50 60 70 80 90 TA − Ambient Temperature − °C 56 100 1k 10k f − Frequency − MHz G006 G005 Figure 6. Figure 7. RSSI OUTPUT CURRENT vs AVERAGE INPUT CURRENT DETERMINISTIC JITTER vs INPUT CURRENT 16 1200 14 Deterministic Jitter − ps RSSI Output Current − µA 1000 800 600 400 200 12 10 8 6 4 2 0 0 0 200 400 600 800 1000 1200 0 400 800 1200 Input Current − µAP−P Average Input Current − µA G007 Figure 8. 8 Figure 9. Submit Documentation Feedback 1600 2000 G008 ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 TYPICAL CHARACTERISTICS (continued) Typical operating condition is at VCC = 3.3 V and TA = 25°C. OUTPUT EYE DIAGRAM AT 4.25 Gbps AND 20-µAp-p INPUT CURRENT Differential Output Voltage − 10 mV/Div Differential Output Voltage − 10 mV/Div OUTPUT EYE DIAGRAM AT 4.25 Gbps AND 10-µAp-p INPUT CURRENT Time − 50 ps/Div Time − 50 ps/Div G009 G010 OUTPUT EYE DIAGRAM AT 4.25 Gbps AND 100-µAp-p INPUT CURRENT OUTPUT EYE DIAGRAM AT 4.25 Gbps AND 1-mAp-p INPUT CURRENT Differential Output Voltage − 50 mV/Div Figure 11. Differential Output Voltage − 50 mV/Div Figure 10. Time − 50 ps/Div Time − 50 ps/Div G011 Figure 12. G012 Figure 13. Submit Documentation Feedback 9 ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 TYPICAL CHARACTERISTICS (continued) Typical operating condition is at VCC = 3.3 V and TA = 25°C. Differential Output Voltage − 50 mV/Div OUTPUT EYE DIAGRAM AT 4.25 Gbps AND 2-mAp-p INPUT CURRENT Time − 50 ps/Div G013 Figure 14. 10 Submit Documentation Feedback ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 APPLICATION INFORMATION Figure 15 shows an application circuit for an ONET4291TA being used in a typical fiber-optic receiver. The ONET4291TA converts the electrical current generated by the PIN photodiode into a differential output voltage. The FILTER input provides a dc bias voltage for the PIN that is low-pass filtered by the combination of the internal 220-Ω resistor and 200-pF capacitor. Because the voltage drop across the 220-Ω resistor is sensed and used by the AGC circuit, the photodiode must be connected to a FILTER pad for the AGC to function correctly. The RSSI output is used to mirror the photodiode average current and must be connected via a resistor to GND. The voltage gain can be adjusted for the intended application by choosing the external resistor. However, for proper operation of the ONET4291TA, ensure that the voltage at RSSI never exceeds VCC – 0.65 V. If the RSSI output is not used, it must be grounded. The OUT+ and OUT– pads are internally terminated by 50-Ω pullup resistors to VCC. The outputs must be ac-coupled (e.g., using C1 = C2 = 0.1 µF) to the succeeding device. An additional capacitor, CNBW, which is differentially connected between the two output pins OUT+ and OUT–, can be used to limit the noise bandwidth and thus optimize the noise performance. C1 0.1 mF OUT+ 3 4 5 6 220 W 200 pF 2 1 ONET 4291TA CNBW 0 to 2 pF Optional PAD#1 VCC 275 pF 10 7 8 9 C2 0.1 mF OUT– RSSI GND S0097-02 Figure 15. Basic Application Circuit ASSEMBLY RECOMMENDATIONS When packaging the ONET4291TA, careful attention to parasitics and external components is necessary to achieve optimal performance. Recommendations that optimize performance include: 1. Minimize total capacitance on the IN pad by using a low-capacitance photodiode and paying attention to stray capacitances. Place the photodiode close to the ONET4291TA die to minimize the bond wire length and thus the parasitic inductance. 2. Use identical termination and symmetrical transmission lines at the ac-coupled differential output pins OUT+ and OUT–. A differential capacitor CNBW can be used to limit the noise bandwidth. 3. Use short bond-wire connections for the supply terminals VCC and GND. Supply-voltage filtering is provided on-chip. Filtering can be improved by using an additional external capacitor. Submit Documentation Feedback 11 ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 CHIP DIMENSIONS AND PAD LOCATIONS 1 10 2 9 3 8 5 y 4 Origin 0,0 4291TAA 1180 mm Overall chip dimensions and depiction of the bond-pad locations are given in Figure 16. Layout of the chip componentry is shown in Figure 17. 6 7 780 mm x M0033-05 Figure 16. Chip Dimensions and Pad Locations y ET 1TA 1180 mm PAD#1 Origin 0,0 780 mm x M0033-06 Figure 17. Chip Layout 12 Submit Documentation Feedback ONET4291TA www.ti.com SLLS670 – SEPTEMBER 2005 Pad Locations and Descriptions for the ONET4291TA PAD COORDINATES SYMBOL TYPE DESCRIPTION x (µm) y (µm) 1 100 1063 GND Supply Circuit ground 2 100 938 GND Supply Circuit ground 3 100 570 OUT+ Analog output Non-inverted data output 4 90 127 VCC Supply 3.3-V supply voltage 5 265 127 FILTER Analog Bias voltage for photodiode 6 515 127 IN Analog input Data input to TIA 7 690 127 RSSI Analog output RSSI output signal 8 680 570 OUT– Analog output Inverted data output 9 680 938 GND Supply Circuit ground 10 680 1063 GND Supply Circuit ground DIE INFORMATION Die size: 1180 µm × 780 µm Die thickness: 8 mils (203 µm) Pad metallization: 99.5% Al, 0.5% Cu Pad size: octagonal pads 120 µm × 100 µm Passivation composition: 6000-Å silicon nitride Backside contact: none Die ID: 4291TAA TO46 LAYOUT EXAMPLES 2. 54 m m Examples for layouts (top view) in 5-pin and 4-pin TO46 headers are given in Figure 18 and Figure 19, respectively. GND OUT+ OUT– VCC RSSI M0034-03 Figure 18. TO46 5-Pin Layout Example Using the ONET4291TA Submit Documentation Feedback 13 ONET4291TA www.ti.com 2. 54 m m SLLS670 – SEPTEMBER 2005 VCC OUT– OUT+ GND M0034-04 Figure 19. TO46 4-Pin Layout Example Using the ONET4291TA 14 Submit Documentation Feedback PACKAGE OPTION ADDENDUM www.ti.com 24-Apr-2019 PACKAGING INFORMATION Orderable Device Status (1) ONET4291TAY ACTIVE Package Type Package Pins Package Drawing Qty DIESALE Y 0 1 Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) TBD Call TI Call TI Op Temp (°C) Device Marking (4/5) -40 to 85 (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of