National Creates CPRI SerDes with 800ps Fiber Delay-Calibration Accuracy

National Semiconductor Corporation (NYSE: NSM), a leading supplier of high- performance analog signal-path products, today introduced an advanced serializer/deserializer (SerDes) for next-generation base station architectures.

National’s new CPRI(R) (common public radio interface) SerDes is the world’s first to guarantee plus or minus 800 ps delay calibration measurement accuracy and exceed all CPRI interface signal voltage and jitter requirements. In addition, the SCAN25100 CPRI SerDes uses dual on-board phase lock loops (PLLs) to automatically synchronize remote radio heads to the digital processing base station. These features enable distributed base station architectures that use multiple antenna technologies to increase radio efficiency, deployment flexibility, and maximize capacity and coverage, while at the same time lowering backhaul, site property and bandwidth costs.

In addition to next-generation GSM, CDMA, W-CDMA, CDMA2000, WiMAX, TD-SCDMA and other base station architectures, National’s SCAN25100 CPRI SerDes is also well-suited for radar, satellite, test equipment, medical imaging, particle accelerator equipment and other high-performance data transfer applications.

Base station vendors and operators must squeeze more capacity and better coverage out of the existing spectrum to cost-effectively deliver rich data and video mobile broadband content. Because today’s modulation and coding techniques are approaching theoretical capacity limits in the frequency and time domains, vendors and operators are turning to the space domain, or distributed base station architectures with multiple antennas, to deliver a compelling DSL-like experience to mobile consumers.

Distributed base station architectures decentralize the radio electronics by moving the radio circuits from the base station to their respective antennas. These remote radio heads (RRHs) are a challenge because they introduce interconnect delay and synchronization issues for the central base station. With its patent-pending precision delay calibration measurement (DCM) circuitry and independent transmit and receive PLLs, National’s SCAN25100 CPRI SerDes accurately measures delays and seamlessly synchronizes the RRHs with the central base station without additional components or complicated system intervention.

A next major step toward improving cellular capacity and coverage at lower per-megabyte cost is to use multi-element beam-steering “smart” antennas and multiple-input, multiple-output (MIMO) antennas within RRHs. These multiple antenna systems, however, can have even tighter timing requirements. Calibrating delays between the base stations and these RRHs is difficult to perform accurately using traditional logic approaches. To track fiber delay changes as small as 200 ps, National’s SCAN25100 CPRI SerDes integrates DCM circuitry to precisely measure base station-to-RRH and RRH-to-RRH fiber delay components with a guaranteed plus or minus 800 ps of accuracy. This patent- pending DCM circuitry also accurately reports the chips own deterministic latency and measures off-chip system delays as well. DCM operates transparently and does not interrupt the CPRI data link. The system software can launch DCM as often as every five milliseconds if required, such as when tracking fiber delay changes over temperature.

National’s SCAN25100 will be demonstrated in National’s booth #506 in Hall A4, at the Electronica trade show in Munich, Germany, from November 14-17.

Key Technical Features of the SCAN25100 CPRI SerDes
In addition to the precision delay calibration and independent transmit and receive PLLs, National’s 2457.6 Mbps, 1228.8 Mbps and 614.4 Mbps SCAN25100 CPRI SerDes integrates challenging high-speed, mixed-signal and clock management, and conditioning features. The SCAN25100 includes programmable serial transmit de-emphasis and receive equalization that exceeds both the CPRI high-voltage and low-voltage standard specifications for jitter and voltage. The chip also integrates 8b/10b encoding, line code violation, comma detect, lock detect, CPRI loss of signal and loss of frame, serial termination, programmable LVTTL or 1.8V CMOS parallel interface, IEEE 1149.1/6 for JTAG SCAN testability and other functions. With superior jitter performance, 8kV electro-static discharge (ESD) and hot-plug protection, the SCAN25100 is an extremely robust interconnect solution for fiber, backplanes and cables more than 15 meters in length.

As an option, the SCAN12100, a reduced-speed 1228.8 Mbps and 614.4 Mbps version with the same features as the SCAN25100, is also available.

To enable optimal system partitioning, National provides CPRI framer protocol as high-level FPGA code with the SCAN25100 and SCAN12100. Customizable, high-level code is ready for integration into existing, low-cost FPGAs. This optimized partitioning integrates the challenging analog SerDes, clocking and DCM functions into the SCAN25100 and SCAN12100 while the reconfigurable FPGA handles the logic functions. This system partitioning provides the highest jitter and timing performance while future-proofing the system design.

For more information on the SCAN25100 CPRI SerDes or to order samples, go online. For more information on the reduced-speed SCAN12100, click here.

About National’s Interface Products
National Semiconductor, the LVDS technology innovator and market leader, offers a wide range of interconnect solutions that transfer high-speed digital signals using world-class analog technology. These solutions help system designers develop high-performance applications in a variety of markets, including communication and industrial systems. The products feature high reliability, low power and low noise, as well as dramatic systems savings in cable and connector costs. National Semiconductor is the world’s largest supplier of high-speed LVDS products, according to Databean’s 2005 Analog IC Market Share survey.

Pricing and Availability
Available now, the SCAN25100 CPRI SerDes is priced at $14.60 and the SCAN12100 is priced at $10.05 each in 1,000-unit quantities.

About National Semiconductor
National Semiconductor, the industry’s premier analog company, creates high-value analog devices and subsystems. National’s leading-edge products include power management circuits, display drivers, audio and operational amplifiers, interface products and data conversion solutions. National’s key analog markets include wireless handsets, displays and a variety of broad electronics markets, including medical, automotive, industrial, and test and measurement applications. Headquartered in Santa Clara, Calif., National reported sales of $2.16 billion for fiscal 2006, which ended May 28, 2006.

National Semiconductor is a registered trademark of National Semiconductor Corporation. CPRI is a trademark of Siemens AG.