Automatic Bench Characterization of USB Transceivers Using LabVIEW, NI TestStand, and PXI
"Our setup is portable, can be deployed for system validation measurements, and has reduced bench characterization time from months to weeks with NI PXI modular instruments."
- Bakkurudeen Ali Jahaya,
ST-Ericssion Asia Pacific Pte Ltd
Designing a flexible bench setup to automatically characterize the design under test (DUT) for various operating conditions to improve quality, reduce cost, and shorten test development time.
Developing a bench setup for performing various measurements of static and dynamic characteristics of the DUT under various operating conditions using NI LabVIEW and NI TestStand software and PXI modular instruments.
Bakkurudeen Ali Jahaya - ST-Ericssion Asia Pacific Pte Ltd
NG Sai Kin - ST-Ericssion Asia Pacific Pte Ltd
Sorin Adrian Badiu - ST-Ericssion Asia Pacific Pte Ltd
Jiang Qian - ST-Ericssion Asia Pacific Pte Ltd
Jerome Tjia - ST-Ericssion Asia Pacific Pte Ltd
Senthil Kumar P - ST-Ericssion Asia Pacific Pte Ltd
Aniruddha Kulkarni - ST-Ericssion Asia Pacific Pte Ltd
Tan Pet Gang Martin - ST-Ericssion Asia Pacific Pte Ltd
LI Guo Hua - ST-Ericssion Asia Pacific Pte Ltd
To characterize the DUT, we used a low- and full-speed USB transceiver and a custom characterization board featuring onboard switches, relays, and interfaces to stream vectors from a high-speed digital I/O card to the DUT.
The setup consists of modular instruments including two NI PXI-4110 programmable power supplies and two NI PXI-4065 digital multimeters (DMMs) for taking current measurements under different test scenarios. We used two NI PXI-6552 high-speed digital I/O modules to provide test patterns for each DUT and reference samples, configuring them to certain modes based on the test specifications. We chose to use NI PXI modular instruments for our application because the devices provided a powerful, low-cost platform for the bench setup and met our system requirements.
Also, the bench setup consists of a high-end digital storage oscilloscope and one external function/arbitrary waveform generator. We used these instruments to obtain measurement results in conjunction with Thermostream for temperature characterization to conduct measurements in the entire specified temperature range from -40 to 85 °C.
Static Characteristics Testing Using PXI Modular Instruments
During the static characteristics test, we configured the DUT and golden, or reference samples, in certain modes based on test specifications using a PXI-6552 digital I/O module. The PXI-6552 reduced the clumsy wiring across the characterization board. We developed sequences based on the test specifications and the characterization plan and controlled power supplies for the DUT and reference sample at several steps to ensure proper chip operation. Additionally, we obtained current measurements using the PXI-4065 DMM. We required multiple voltages for the DUT and controlled them by test sequences using NI TestStand. We obtained measurements for several modes of operation of the DUT and logged the results into a dedicated database server wired on a local area network (LAN) using NI TestStand.
Dynamic Characteristics Testing NI Software and PXI
The bench setup also verifies dynamic parameters of the DUT. We used the PXI-6552 modules to create user-defined patterns based on USB specifications that were downloaded to the DUT and reference sample. We used a high-end oscilloscope with the bench setup to measure dynamic parameters such as rise time, fall time, and propagation delay of USB differential signals. We developed the instrument driver for the oscilloscope, signal generator, and Thermostream using LabVIEW, NI LabWindows™/CVI, and NI TestStand software. The main objective of this bench setup is to obtain large quantities of data with high accuracy for different silicon samples at various voltage and temperature settings.
Electrical Compliance Testing for USB 2.0
USB 2.0 specifies three different data rates – low speed at 1.5 Mbps, full speed at 12 Mbps, and high speed at 480 Mbps. All three data rates can exist concurrently in a network of USB devices. This gives the user flexibility to mix and match peripherals with different needs in terms of speed and throughput. Flexibility is one of the major advantages of USB because of the stringent regulations and compliance testing mandated by the USB-IF. To prove compliance and achieve certification by the USB-IF requires the device to pass signal integrity, current and voltage parametric, and data integrity tests using approved USB-IF test tools.
For signal quality testing, we used an oscilloscope to observe the transmitted and received signals. The oscilloscope allows us to measure a range of parameters, including signal eye diagram, end of packet width, signaling rate, rise/fall times, crossover voltage, and jitter. We stored the data collected during the measurement in buffer memory and used the USB-IF tool in NI TestStand to analyze the signal integrity and generate a report with pass/fail criteria. The bench setup provided full-featured USB test solutions by integrating USB-IF test tools with NI TestStand and NI LabVIEW.
Report Generation and Analysis
We stored the bench characterization test steps and measurement results in the dedicated database server for data management and analysis, which we can log to using NI TestStand. Our team developed a proprietary tool for extracting information from the database using MySQL as the DBMS, analyzing the data, and producing statistical calculations such as process capability (Cpk) using PHP and HTML to generate test reports. In addition to report generation and analysis, the bench setup is capable of account management with user permissions and rights to view specific data based on user privileges. The user can select and generate reports with specific attributes, highlight bad process capability, and export raw data to Microsoft Excel.
Reduced Test Time and Improved Quality of Silicon Characterization
Our system setup has been integrated with NI PXI modular instruments to improve quality in bench characterization. Our setup is portable, can be deployed for system validation measurements, and has reduced bench characterization time from months to weeks with NI PXI modular instruments. In addition to reduction in time and effort, the measurements obtained from the bench characterization setup correlate with automatic testing equipment (ATE) setup, which normally costs much more. Test engineers can quickly view results to determine whether additional tests are required, which reduces overall test time. Finally, our report generation method improves data management and provides test results over the Internet.
The mark LabWindows is used under a license from Microsoft Corporation. Windows is a registered trademark of Microsoft Corporation in the United States and other countries.
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