SY88993AL 3.3V 3.2Gbps High-Speed Limiting Post Amplifier with High Input Sensitivity General Description Features The SY88993AL limiting post amplifier, with its wide bandwidth, is ideal for use as a post amplifier in fiber-optic receivers with data rates up to 3.2Gbps. Signals as small as 4mVPP can be amplified to drive devices with CML inputs or AC-coupled PECL inputs. The SY88993AL generates a chatter-free Loss-of-Signal (LOS) open collector TTL output using an external resistor, as shown Figure 1. The SY88993AL incorporates a programmable level detect function to identify when the input signal has been lost. This information can be fed back to the /EN input of the device to maintain stability under loss of signal conditions. Using LOSLVL pin the sensitivity of the level detect can be adjusted. The LOSLVL voltage can be set by connecting a resistor divider between VCC and VREF, Figure 5. • • • • • • • • Datasheets and support documentation can be found on Micrel’s web site at: www.micrel.com. Up to 3.2Gbps operation Low noise CML data outputs Chatter-Free LOS generation Open Collector TTL LOS output TTL /EN Input Differential PECL inputs for data Single 3.3V power supply Available in a tiny 10-pin (3mm x 3mm) MSOP Applications • • • • • • PON SFP/SFF/GBIC optical transceivers Gigabit Ethernet 1X and 2X Fibre Channel SONET/SDH: OC 3/12/24/48 – STM 1/4/8/16 Line driver and line receiver Markets • FTTX • Datacom/Telecom Figure 1. LOSLVL resistor configuration Micrel Inc. • 2180 Fortune Drive • San Jose, CA 95131 • USA • tel +1 (408) 944-0800 • fax + 1 (408) 474-1000 • http://www.micrel.com September 2008 M9999-093008-A [email protected] or (408) 955-1690 Micrel, Inc. SY88993AL Block Diagram Detailed Description resistor, as shown in Figure 1. LOS is used to determine that the input amplitude is large enough to be considered a valid input. LOS asserts high if the input amplitude falls below the threshold sets by LOSLVL and de-asserts low otherwise. LOS can be fed back to the enable bar (/EN) input to maintain output stability under a loss of signal condition. /EN de-asserts the true output signal without removing the input signals. Typically, 5.6dB LOS hysteresis is provided to prevent chattering. The SY88993AL is a high-sensitivity limiting post amplifier that operates from a single +3.3V power o o supply, over temperatures from –40 C to +85 C. Signals with data rates up to 3.2Gbps and as small as 4mVPP can be amplified. Figure 2 shows the allowed input voltage swing. The SY88993AL generates a LOS output. LOSLVL sets the sensitivity of the input amplitude detection. Input Amplifier/Buffer Figure 3 shows a simplified schematic of the SY88993AL’s input stage. The high-sensitivity of the input amplifier allows signals as small as 4mVPP to be detected and amplified. The input amplifier also allows input signals as large as 1800mVPP. Input signals below 6mVpp are linearly amplified with a typical 38dB differential voltage gain. Since it is a limiting amplifier, the SY88993AL outputs typically 800mVPP voltagelimited waveforms for input signals that are greater than 10mVPP. Applications requiring the SY88993AL to operate with high-gain should have the upstream TIA placed as close as possible to the SY88993AL’s input pins to ensure the best performance of the device. Loss-of-Signal Level Set The SY88993AL incorporates a programmable level detect function to identify when the input signal has been lost. This information can be fed back to the /EN input of the device to maintain stability under loss of signal conditions. Using LOSLVL pin the sensitivity of the level detect can be adjusted. The LOSLVL voltage can be set by connection a resistor divider between VCC and VREF, Figure 5. Hysteresis The SY88993AL typically provides 5.6dB LOS electrical hysteresis. By definition, a power ratio measured in dB is 2 10log (power ratio). Power is calculated as V IN/R for an electrical signal. Hence, the same ratio can be stated as 20log (voltage ratio). While in linear mode, the electrical voltage input changes linearly with the optical power and therefore, the ratios change linearly. Thus, the optical hysteresis in dB is half the electrical hysteresis in dB given in the data sheet. Since the SY88993AL is an electrical device, this data sheet refers to hysteresis in electrical terms. With 5.6dB LOS hysteresis, a voltage factor of about 2 is required to assert or de-assert LOS. Output Buffer The SY88993AL’s CML output buffer is designed to drive 50Ω lines. The output buffer requires appropriate termination for proper operation. An external 50Ω resistor to VCC for each output pin provides this. Figure 4 shows a simplified schematic of the output stage. Loss-of-Signal The SY88993AL generates a chatter-free LOS opencollector TTL output which requires an external pull-up September 2008 2 M9999-093008-A [email protected] or (408) 955-1690 Micrel, Inc. SY88993AL Ordering Information Part Number Package Type Operating Range Package Marking Lead Finish K10-1 Industrial 993L with Pb-Free bar-line indicator Pb-Free NiPdAu K10-1 Industrial 993L with Pb-Free bar-line indicator Pb-Free NiPdAu SY88993ALKG SY88993ALKGTR (1) Note: 1. Tape and reel. Pin Configuration 10-Pin MSOP (K10-1) Pin Description Pin Number Pin Name 1 /EN TTL (Input): Output enable (Active Low). 2 DIN Data (Input): Data input. 3 /DIN Data (Input): Complementary data input. 4 VREF 5 LOSLVL 6 GND Ground. 7 LOS TTL Output (Open Collector): Loss-of-Signal indicator (Active High). 8 /DOUT CML (Output): Inverting data output. 9 DOUT CML (Output): Data output. 10 VCC September 2008 Pin Function Output: Reference voltage output for LOS Level Set (See Figure 3). Input: Loss-of-Signal Level Set Power Supply: Positive power supply. 3 M9999-093008-A [email protected] or (408) 955-1690 Micrel, Inc. SY88993AL Absolute Maximum Ratings(1) Operating Ratings(2) Supply Voltage (VCC) ......................................... 0V to +4.0V Input Voltage (DIN, /DIN) ...................................... 0V to VCC Lead Temperature (soldering, #sec.) ......................... 260°C Storage Temperature (Ts) ........................... –55°C to +85°C Supply Voltage (VIN) ..................................... +3.0V to +3.6V Ambient Temperature (TA) .......................... –40°C to +85°C Junction Thermal Resistance MSOP (θJA) ......................................................113°C/W o MSOP (ψJB) ....................................................... 96 C/W DC Electrical Characteristics VCC = +3.3V ±10%; RLOAD = 50Ω to VCC; TA = -40°C to +85°C, unless noted. Typical values at Vcc = 3.3V, TA = 25°C Symbol Parameter Condition ICC Power Supply Current No output load. IOH LOS Output Leakage Vcc = 3.6V LOSLVL LOSLVL Level VOH Output HIGH Voltage VOL Output LOW Voltage ZO Single-Ended Output Impedance VREF Reference Voltage VOFFSEST Differential Output Offset VCMR Common Mode Range Min Typ Max Units 40 55 mA 100 µA VCC V VCC–20 VREF VCC–5 VCC mV Note 9 Vcc-350 VCC–400 Vcc-475 mV Note 10 40 50 60 Ω VCC–1.38 VCC–1.32 VCC–1.26 V ±80 mV VCC–0.2 V GND ±2 TTL DC Electrical Characteristics VCC = +3.3V ±10%; RLOAD = 50Ω to VCC; TA = -40°C to +85°C, unless noted. Symbol Parameter VIH /EN Input HIGH Voltage VIL /EN Input LOW Voltage IIH /EN Input HIGH Current IIL /EN Input LOW Current Condition Min Typ Max Units 0.8 V VIN = 2.7V 20 µA VIN = VCC 100 µA 2.0 VIN = 0.5V -300 µA Notes: 1. Permanent device damage may occur if absolute maximum ratings are exceeded. This is a stress rating only and functional operation is not implied at conditions other than those detailed in the operational sections of this data sheet. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 2. The data sheet limits are not guaranteed if the device is operated beyond the operating ratings. September 2008 4 M9999-093008-A [email protected] or (408) 955-1690 Micrel, Inc. SY88993AL AC Electrical Characteristics VCC = +3.3V ±10%; RLOAD = 50Ω to VCC; TA = -40°C to +85°C, unless noted. Symbol Parameter Condition Min Typ LOSAH High LOS Assert Level VLOSLVL = VCC 30 43 LOSDH High LOS De-assert Level VLOSLVL = VCC 83 95 mVPP HYSH High LOS Hysteresis 2 5.6 8 dB LOSAM Medium LOS Assert Level VLOSLVL = VCC – 400mV 20 31 LOSDM Medium LOS De-assert Level VLOSLVL = VCC – 400mV 55 65 mVPP HYSM Medium LOS Hysteresis 2 5.6 8 dB LOSAL Low LOS Assert Level VLOSLVL = VCC – 800mV 10 19 LOSDL Low LOS De-assert Level VLOSLVL = VCC – 800mV HYSL Low LOS Hysteresis PSRR Power Supply Rejection Ratio Note 4 35 tOFFL LOS Release Time Minimum Input Note 5 0.1 tOFFH LOS Release Time Maximum Input Note 5 0.1 0.5 µs tONL LOS Assert Time Note 5 0.2 0.5 µs tr , tf Differential Output Rise/Fall Time (20% to 80%) Note 6 60 120 Ps VID Input Voltage Range 1800 mVPP VOD Differential Output Voltage Swing 950 mVPP VSR LOS Sensitivity Range 50 mVPP AV(Diff) Differential Voltage Gain 38 DB B–3dB 3dB Bandwidth 2.5 GHz S21 Single-Ended Small Signal-Gain 32 dB 2 700 mVPP mVPP mVPP 45 mVPP 5.6 8 dB 800 4 26 Units 31 4 Note 7, 8, 9, 10 Max dB 0.5 µs Notes: 4. Input referred noise = RMS output noise/low frequency gain. Input referred, 55MHz. 5. Input is a 200MHz square wave, tr < 300ps. 6. With input signal VID > 50mVPP with 50Ω load. 7. Input is a 200MHz square wave, tr < 300ps, 50Ω load. 8. VID > 10mVPP. 9. Output levels are based on 50Ω impedance. If the load impedance is different, the output level will be changed. 10. See output structure. September 2008 5 M9999-093008-A [email protected] or (408) 955-1690 Micrel, Inc. SY88993AL Typical Characteristics Functional Characteristics September 2008 6 M9999-093008-A [email protected] or (408) 955-1690 Micrel, Inc. SY88993AL Figure 2. VIS and VID Figure 4. Differential Output Configuration Figure 3. Differential Input Configuration Notes: 1. Resistor Divider = R2/ (R1 + R2) 2. R1 + R2 ≥ 5kΩ Figure 5. LOSLVL Circuit September 2008 7 M9999-093008-A [email protected] or (408) 955-1690 Micrel, Inc. SY88993AL Package Information 10-Pin MSOP (K10-1) MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA TEL +1 (408) 944-0800 FAX +1 (408) 474-1000 WEB http://www.micrel.com The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use. Micrel reserves the right to change circuitry and specifications at any time without notification to the customer. Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s use or sale of Micrel Products for use in life support appliances, devices or systems is a Purchaser’s own risk and Purchaser agrees to fully indemnify Micrel for any damages resulting from such use or sale. © 2008 Micrel, Incorporated. September 2008 8 M9999-093008-A [email protected] or (408) 955-1690