Agilent N4970A PRBS Generator 10 Gb/s User Guide
Notices © Agilent Technologies, Inc. 2012 No part of this manual may be reproduced in any form or by any means (including electronic storage and retrieval or translation into a foreign language) without prior agreement and written consent from Agilent Technologies, Inc. as governed by United States and international copyright laws. Manual Part Number N4970-91021 Edition Second edition, May 2013 Agilent Technologies, Deutschland GmbH Herrenberger Str.
Safety Summary General Safety Precautions General Ground the Instrument The following general safety precautions must be observed during all phases of operation of this instrument. Failure to comply with these precautions or with specific warnings elsewhere in this manual violates safety standards of design, manufacture, and intended use of the instrument. This product is a Safety Class 1 product (provided with a protective earthing ground incorporated in the power cord).
Symbols on Instruments Indicates warning or caution. If you see this symbol on a product, you must refer to the manuals for specific Warning or Caution information to avoid personal injury or damage to the product. C-Tick Conformity Mark of the Australian ACA for EMC compliance. CE Marking to state compliance within the European Community: This product is in conformity with the relevant European Directives: EMC Directive 2004/108/EC and Low Voltage Directive 2006/95/EC.
Environmental Information This product complies with the WEEE Directive (2002/96/EC) marketing requirements. The affixed label indicates that you must not discard this electrical/electronic product in domestic household waste. Product category: With reference to the equipment types in the WEEE Directive Annexure I, this product is classed as a “Monitoring and Control instrumentation” product. Do not dispose in domestic household waste.
Contents Contents 1 2 Getting Started ......................................................................................................... 9 1.1 Unpacking and Installation ............................................................................ 9 1.2 Important Notes............................................................................................. 10 1.3 Performance Recommendations................................................................. 10 N4970A Operation Overview .....
Getting Started 8 PRBS Generator 10 Gb/s User Guide
Getting Started 1 Getting Started 1.1 Unpacking and Installation The N4970A PRBS generator 10 Gb/s is shipped with all the accessories required for the self-test mode and verification. The shipment includes: • • • • N4970A PRBS generator 10 Gb/s AC power converter module AC power cord CD containing the N4970A user guide and N4970A data sheet If this product is not used as specified, the protection provided by the equipment could be impaired.
Getting Started In an ESD-safe environment, carefully remove the N4970A from the packaging. Install on a flat surface with unobstructed air flow to the back panel. Make all RF connections between the N4970A and the DUT or test equipment BEFORE applying AC power by plugging the converter module into the N4970A. Also, remove AC power from the N4970A instrument before disconnecting any RF connections.
N4970A Operation Overview 2 N4970A Operation Overview The N4970A is a Pseudo Random Bit Stream (PRBS) generator with an internal clock that can be factory set from a selection of frequencies around 10 GHz, and can also be user-configured to use a 0.05 to 12.5 GHz clock signal from an external source. The N4970A features low jitter, fast rise and fall times, and a clean eye pattern. The source provides five selectable pattern lengths and three selectable mark densities.
N4970A Operation Overview 2.2 N4970A System Overview The N4970A provides a Pseudo Random Bit Stream (PRBS) referenced to either the factory-set internal clock frequency or an external clock (0.05 GHz to 12.5 GHz). The N4970A generates a bit stream equal to the clock frequency, eg: 9.95328 GHz = 9.95328 Gb/s (SONET 10G). The PRBS pattern length and mark density features can be selected by the user. The pattern length and mark density settings are indicated on the front panel of the N4970A.
N4970A Operation Overview Figure 1. 10 Gb/s eye output 2.3 Options The N4970A is available with the following build options: • • • • • • • • PRBS Generator 10 Gb/s User Guide Standard: 10 Gb/s data rate operation 300 mV p-p output N4970A-010: extended amplitude range 750 mV p-p output N4970A-301: internal clock frequency at 10.66423 GHz N4970A-302: internal clock frequency at 10.51875 GHz N4970A-303: internal clock frequency at 11.09573 GHz N4970A-304: internal clock frequency at 9.
N4970A Operation Overview 2.4 Front Panel Quick Reference Figure 2. N4970A front panel RESET: A momentary reset switch provides a means to restart the bit stream from an all zero condition. Output: The PRBS signal is available as a differential signal on the SMA female output terminals. Terminate unused outputs. Impedance: 50 Ω Max DC: ±5V Nominal DC: 0V AC Level: > 300 mV p-p typical, single-ended > 750 mV p-p typical, single-ended (Option 010) ESD sensitive; terminate if unused. DC Blocked.
N4970A Operation Overview LED indicators: Eight LED annunciators are provided on the front panel. The first five indicate the selected pattern length. The next three indicate the selected mark density as illustrated below. Figure 3. N4970A front panel 2.5 Rear Panel Quick Reference Figure 4. N4970A rear panel Power: Negative 5 Vdc @ 1 A (center pin negative) is supplied, by the power supply module, to this terminal to power the PRBS source. Use only the AC/DC adapter provided with the N4970A.
N4970A Operation Overview Rear connector: Eight sets of pins are provided to select the pattern length and mark density. A separate pair of pins is provided to allow remote reset. Two jumpers are used to select the desired pattern length and mark density. Install the jumpers in the desired positions for stand-alone operation. Refer to Figure 5. A cable can be connected to the pins for remote operation. CKO output: A female SMA connector is provided for the internal clock output.
N4970A Operation Overview CKO/16 output: A female SMA connector provides a divided-by-16 clock output (CKO/16 = CKI div 16) for triggering. Impedance: 50 Ω Max DC: ±5V Nominal DC: 0V AC output: 600 mV p-p nominal DC Blocked. Figure 5.
N4970A Operation Overview 2.6 Safety and Regulatory This product has been designed and tested in accordance with accepted industry standards, and has been supplied in a safe condition. The documentation contains information and warnings that must be followed by the user to ensure safe operation and to maintain the product in a safe condition. Do not remove instrument covers. There are no user serviceable parts within.
Performance Specifications 3 Performance Specifications Specifications describe the instrument’s warranted performance. Nonwarranted values are stated as typical. All specifications are valid in a range from 10 °C to 40 °C ambient temperature after a 30 minute warm-up phase. 3.1 General Table 1.
Performance Specifications 3.2 N4970A PRBS Generator Specifications Table 2. N4970A PRBS generator specification table Parameter Specification Data rate 0.5 to 12.5 Gb/s1 External clock input rate 0.5 to 12.5 GHz External clock input power required +10 dBm (2 V p-p) typical < 1.0 GHz +3 dBm (890 mV p-p) typical ≥ 1.0 GHz Internal clock rate Single frequency internal oscillator, specify when ordering Default 10.0 GHz Option 301 – 10.66423 GHz Option 302 – 10.51875 GHz Option 303 – 11.
Operation 4 Operation The following section provides more detailed information regarding the use of the N4970A. 4.1 General Information The N4970A should be used in accordance with the following: • • • • • • • PRBS Generator 10 Gb/s User Guide Read and follow operating instructions; do not exceed min/max specifications. Use ESD protection at all times, but especially when handling RF input/outputs; ground coaxial cable conductor pins before use to remove static buildup.
Operation 4.1.1 Performance Recommendations Follow the following recommendations for best performance: 1. When using differential mode connection for OUT/OUT ¯¯¯, ensure the cables are phase balanced. If the electrical length of one cable is a significant fraction of a unit interval longer than the other, the quality of the differential signal will be degraded. 2. Keep cable lengths short and minimize number of cable bends. 3.
Operation 1. Remove any dust or loose particles using a low-pressure air source. 2. Moisten a lint-free swab with isopropyl alcohol. Do not saturate the swab. 3. Minimize the wicking of the alcohol into the connector structure. 4. Clean the mating plane surfaces and threads. 5. Allow alcohol to evaporate, and then use a low-pressure air source to blow surfaces clean. 6. Make sure no particles or residue remains. 7. Inspect connector for damage. 4.
Operation 4.3 Resetting the N4970A The reset pins on the back panel can be used to reset the N4970A without using the front panel pushbutton switch. The design of the N4970A has the pin below the "Reset" pin assigned to ground so that an external reset switch can be connected with a 2 pin connector. Refer to Figure 6. 4.4 Input and Output Connectors Table 3.
Operation Connector Description DC Level DC Level Z0 Notes M1 – M3 Mark/space select N/A N/A N/A Selected by closure to lower pin. Refer to Figure 6. Reset Reset PRBS N/A N/A N/A Selected by closure to lower pin. Refer to Figure 6. The turning of the cable or connector while connecting the coupling nut of the connector turns the center contacts while they are engaging. This wears the plating, thereby decreasing the signal integrity and operating life of the connectors.
Operation Figure 7. Verification setup Correct pattern length is determined by confirming that the tone spacing on the spectrum analyzer equals (Output_Bit_Rate/(2n-1)), where n is the specific pattern length. As an example, at 10 Gb/s the tone spacing for a (231-1) pattern should be ~ 4.66 Hz (refer to Table 4 for tone spacings).
Operation Mark density is a measure of the number of logic 1's vs. total logic 1's and logic 0's. Standard PRBS patterns consist of equal numbers of 1's and 0's resulting in a mark density of 1/2. The density of logic 1's and 0's can be qualitatively confirmed using a high speed sampling scope. A mark density of 1/2 will result in an output eye centered about 0 V.
Operation 4.6 Simple Functional Example of N4970A use A typical residual or additive jitter test system is shown in Figure 8. Additive jitter measurements require a precise, low jitter clock. A high-quality external clock may decrease PRBS jitter. Figure 8. N4970A generic test example experimental setup To maintain the integrity of the system the user must select the appropriate connectors and minimize the length of microwave cabling.
Returning the N4970A to Agilent Technologies 5 Returning the N4970A to Agilent Technologies If the N4970A fails system verification and you cannot correct the problem, return it to Agilent Technologies for repair following the steps shown below. 1. Record all symptoms. 2. Contact Agilent Technologies at http://www.agilent.com/find/assist. 3. Use the original packing material or comparable packing material to ship the instrument to Agilent Technologies.
© Copyright Agilent Technologies 2012 Second edition, May 2013 Printed in Germany