Agilent Technologies Serial ATA Backgrounder - Thorough Characterization and Validation of Serial ATA Designs
Feburary 01, 2010
The Serial ATA International Organization (SATA-IO) has released the SATA Revision 3.0 specification, providing support for 6 Gb/s data transfer between hosts, devices and port multipliers. At higher data rates, power consumption and emissions become more of a concern on system budgets. Link designers seek to find optimum voltages, emphasis levels and edge rates to manage these challenging design limits while ensuring functional protocol operation at the receiver. The SATA-IO has designed a comprehensive interoperability test program to assess the electromechanical physical layer design limits, protocol state machine branching and command execution as well as system-level functional operation. The goal of the program is to improve interoperability between SATA products in the market, and to provide an equitable test vehicle through which all vendors' products can be fairly compared to the provisions of the specification. Several new features and test requirements exist within the SATA Revision 3.0 specification, which require new tools and new validation methods to assess accurately.
SATA physical layer validation and compliance can be segmented into three areas: transmitter characterization (PHY/TSG/OOB), receiver characterization (RSG), and Impedance/Return Loss characterization (RX/TX). The specification aims to balance the design budgets among the transmitter, receiver and interconnect channel to ensure zero-sum accounting for key attributes such as jitter and minimum differential amplitude, which directly influence interoperability between products. SATA protocol layer validation can also be segmented into host and device digital tests. If all products adhere to the SATA specifications, then by definition, all SATA products should work together in any system configuration. Agilent offers a complete portfolio of tools for testing SATA physical layer and protocol layer solutions. On the physical layer Agilent provides test solutions for 1.5 Gb/s, 3 Gb/s, and 6 Gb/s data rates and provides official SATA-IO GOLD suite testing for all three physical layer areas at the bi-annual SATA-IO Interoperability Workshops. Several key certified test labs also utilize Agilent equipment to provide Interoperability test support for SATA-IO throughout the year. Utilizing the same equipment configurations and test suites in your lab allows you to have greater confidence in your design margins relative to the specification requirements well ahead of official certification, helping speed your time-to-market and time-to-profit.
"Having advance access to measurements enables developers of cutting-edge solutions to address potential design issues early in the design cycle and get products to market faster," said Min-Jie Chong, program manager SATA applications at Agilent. "Agilent offers a full range of SATA test capabilities and performance in presenting industry-leading serial data generation and analysis test capabilities to accelerate SATA 1.5 Gb/s, 3 Gb/s and 6 Gb/s tests."
Transmitter (PHY/TSG/OOB) Compliance Testing
Validating Serial ATA performance involves characterizing transmitter signal speed, stability, output levels and amplitude imbalance, rise/fall times and imbalance, common mode voltages, and jitter. Manually making these measurements is time consuming and prone to error. An automated method to trigger properly and measure as defined by SATA-IO will allow analyzing the complex traffic on the Serial ATA bus efficiently and accurately.
Receiver (RSG) Compliance Testing
The receiver test is a bit more complicated than the transmitter test, due to the DUT's task within a digital transmission system: the extraction of the digital content from its input signal with a specified, very low frame error ratio (FER); the difficulty of this task is, that the signal is heavily deteriorated after it left the (non-ideal) transmitter and propagated through a lossy channel with (see Figure 1): ); the difficulty of the test is, that it is necessary to stimulate the RX under test with a deliberately deteriorated signal and check the quality of the conversion, utilizing the implemented loop back, which in the case of S-ATA only allows to use frame error ratio (FER) instead of BER as a figure of merit.
Figure 1: (a) receiver input with degraded performance due to lossy cables or test fixtures
Impedance/Return Loss (TX/RX)
As data rates increase, designers need to pay special attention to their board design to minimize signal integrity problems. Long trace lengths cause signal attenuation, rise-time degradation, and jitter. Impedance transitions between a trace and via can cause reflections and crosstalk. Designers need to utilize tools that are more commonly used by high-frequency engineers -- a time-domain reflectometer (TDR), a vector network analyzer (VNA), and high-frequency simulation software.
Host and Device Digital Tests
The Agilent U3051A and U3052A BusXpert protocol analyzers are able to display live performance statistics during capture and provide in-depth protocol analysis on the captured data. Command throughput, frame turn-around time, queue depth and other analytical information are calculated and hyperlinked to navigate easily within the trace data. The statistical reports can also be exported to XML, XLS, and HTML for exterior reporting. These metrics allow customers to look for potential areas of interest and benchmark products under test.
Figure 2: S-parameters can be automatically generated from the 86100C Infiniium DCA-J TDR measurement.
Complete, reliable test coverage
What makes Agilent's design and test solutions so compelling is that they are the best tools, in every category, to meet the challenges presented by Serial ATA. Agilent's participation in SATA-IO, developing thorough SATA-IO approved Method of Implementations (MOIs), and keeping Agilent solutions SATA-IO verified, provides the solution that is needed to guarantee the design for interoperability and system quality.
The quality of Agilent solutions is the key to easier, faster and more confident testing of Serial ATA designs. That takes strain out of engineering and lowers development costs. Accurate results reduce the number of design cycles to help get to market faster, and they ensure robust products that uphold one's hard-won lead in the market.
Agilent SATA Test Solutions
Accurate impedance measurements
For quick impedance measurements, a TDR is commonly used. By injecting a fast pulse into the design, the TDR measures the reflected signal to determine impedance versus time, which is easily converted to the distance domain. Likewise, measuring the signal at the far end of the circuit defines the insertion loss profile. TDR displays are intuitive, the measurement setup is easy, and the calibration approach is simple.
The Agilent 86100C Infiniium DCA-J with the 54754A differential TDR/TDT module makes quick work of interconnect analysis. To improve accuracy, it utilizes a unique calibration process that removes the effects of cabling, allowing to isolate the device from the test system. By switching to frequency mode, engineers can also examine the S-parameters for transmission and impedance performance of channels, cables, and connectors (see Figure 2). Digital engineers, already familiar with oscilloscopes, can quickly see the relationships between frequency and time effects without having to purchase and learn new equipment.
Figure 3: SATA design and test solutions
The Agilent 86100C Infiniium DCA-J can view electrical waveforms with bandwidths up to 93 GHz. The DCA-J is an ideal tool for making signal integrity and jitter measurements for high speed signaling standards. Complete jitter analysis is simplified via a one-button approach to review the random and deterministic jitter components. With the Agilent 54754A Differential TDR/TDT module, engineers can characterize impedance and crosstalk in channels and view the results in either time-domain or as S-parameters in the frequency domain.
SATA signal integrity engineers who are hurdling the multi-gigabit/s barrier look to ADS for the correct treatment of high-speed effects like distortion, mismatch, and crosstalk. Uniquely, ADS integrates accurate system, circuit, and EM simulators so you can not only get the right answers but also get them faster by avoiding error-prone and time-consuming data transfer between a collection of point tools.
The Agilent 90000 Series Infiniium oscilloscopes deliver the highest performance real-time measurement system available. The Infiniium 90000 Series offers the industry's lowest noise floor, jitter noise floor, and trigger jitter, making it the ideal tool for signal integrity and jitter measurements. Models are available from 2.5 GHz to 13 GHz, and can be upgraded in bandwidth for future needs.
The N5411B SATA Compliance Test Software for Infiniium oscilloscopes provides a fast and easy way to validate and debug SATA 1.5Gb/s (Gen 1), 3.0Gb/s (Gen2) and 6.0Gb/s (Gen3) silicon, host bus adapter, port multiplier, high-density disk drive, solid-state disk drive or optical disk drive. The N5411B software provides automated compliance test support for the i (internal), m(eSATA) and x(SAS attachment) interfaces points, and displays the results in a flexible report format. In addition to the measurement data, the report provides a margin analysis that shows how closely the device passed or failed each test.
The J-BERT N4903B provides complete jitter tolerance testing of serial bus interfaces operating up to 14.2 Gb/s. It is the ideal solution for R&D and test engineers, who need to characterize and test compliance of multi-gigabit digital components, devices and subsystems. It provides integrated, calibrated jitter sources for receiver tolerance testing. Flexible SSC generation is available. For OOB tests a second channel option is available. The BERT analyzer is able to handle 8b/10b coded pattern streams with retimed loopback from the device.
The Agilent N5990A test automation software platform is the most powerful tool for serial and multi-lane gigabit testing. It is the unique universal platform for testing a wide range of digital buses such as SATA, PCI Express®, USB or HDMI. The N5990A can be tailored to individual test needs with the flexible test sequenzer and controls all instruments needed for your tests. The configurable database interface of the N5990A test automation platform enables the convenient storage of all test results. The N5990A software takes test automation to the next level of performance and convenience. It addresses specific bus standards by individual software modules with the same look and feel. All modules share the same user interface which increases efficiency and productivity.
SerialTek's BusXpert SAS/SATA test solutions represent the industry's most advanced protocol analyzer. Hardware and software innovations such as a PCI Express to Host connection, Trace Indexing, and microprocessor-assisted InstaSearch improve the user experience when developing and debugging with a protocol analyzer. These technologies along with the industry's largest buffer size, up to 36GB, and a simple, robust GUI allow the BusXpert to efficiently display, manipulate, trigger, and save traces at speeds not seen in any other competitive offering.
When timing and performance requirements are critical, for example in high-speed serial bus applications like PCI Express or Serial ATA, the fast rise times and low intrinsic jitter of the 81134A allow the precise and in-depth characterization of devices, e.g. receivers or backplanes. On top of that, it allows to generate application-specific signal levels like pre- and de-emphasis (PCI Express) or squelch (Serial ATA). The Agilent 81134A allows to test the DUT instead of the pulse or data source.
As the combination of both time-domain and frequency domain analysis becomes more important, the need for multiple test systems becomes difficult to manage. A single test system that can fully characterize differential high-speed digital devices such as SATA cables, while leaving domain and format of the analysis up to the designer, is a very powerful tool. Agilent's Physical Layer Test System (PLTS) is designed specifically for this purpose.
Further information on Agilent's SATA solutions can be found online at www.agilent.com/find/SATA
For any questions about SATA design and test, consult the Agilent discussion forum online at www.agilent.com/find/forums
Agilent's Digital Test Standards Program
Agilent's measurement solutions and services development for digital applications is driven and supported by the work that Agilent's experts do in the various international standard committees. The Agilent Standards Program for digital applications comprises Double Data Rate (DDR) memory, PCI Express®, DisplayPort, Universal Serial Bus (USB), Serial ATA (SATA), Serial Attached SCSI (T10)
High-Definition Multimedia Interface (HDMI®), DigRF and optical transceiver test. Our experts are in the Board of Directors in Joint Electronic Devices Engineering Council (JEDEC), PCI-SIG® and Video Electronics Standards Association (VESA). Agilent is contributing member in Serial ATA International Organization (SATA-IO), USB-Implementers Forum (USB-IF) and Mobile Industry Processor Interface (MIPI) Alliance.
Agilent's involvement in these standards gives Agilent and its customers, the computing and communication component vendors to the electronics consumer market, two main advantages:
- First, it enables us to bring the right products to the market when our customers need them. We aim to be first to market with our solutions so our customers can be first to market with their products ensuring standard compliance.
- Second, with Agilent's involvement in plug-fests, workshops and seminars we are in the unique position to develop solutions that evolve with the standards, giving the ability to design the best products with the highest confidence.
PCI Express, PCIe and PCI-SIG are registered trademarks and trademarks respectively of the PCI-SIG.
HDMI, the HDMI logo and High-Definition Multimedia Interface are trademarks or registered trademarks of HDMI Licensing LLC.
For further information about Agilent's optical component solutions visit: www.agilent.com/find/sata_images
Janet Smith, Americas
Sarah Calnan, Europe
Iris Ng, Asia