SDAIII and QualiPHY Software: Oscilloscope Eye Diagrams for Compliance and Debug

Figure 1. SDAIII enables eye diagrams and eye
measurements of four lanes of  streaming data.

Besides the serial TDME and TDMP options discussed earlier, there are other ways to generate eye diagrams on your Teledyne LeCroy oscilloscope for compliance testing and debug.

SDAIII Serial Data Analysis Software

SDAIII offers the most comprehensive eye diagram capabilities for Teledyne LeCroy oscilloscopes, with tools for optimizing the displayed eye that are especially useful to high-speed serial data analysis.

Which Virtual Probing Method to Use?

 

Virtual probing lets you "probe" where a probe
can't reach, or compensate signals by deembedding
or simulating devices and channels.

A great feature of Teledyne LeCroy oscilloscopes is the ability to apply virtual probing to compensate an input signal, whether by deembedding fixtures from the signal path, or simulating a “missing” component. It is especially helpful in cases where the signal is difficult to probe at the ideal location, hence the concept of “virtual” probing.

For example, because the JEDEC electrical specifications are defined at the balls of the DDR DRAM, it is often necessary to use the virtual probing capabilities of the oscilloscope to get the best representations of DDR signals to be analyzed with DDR Debug Toolkit or QualiPHY compliance software.

Here, we’ll give an overview of the virtual probing methods that become available with the installation of the SDAIII-CompleteLinQ or VirtualProbe software options, and some guidance as to which method is best to use in which case. And although we’ll show examples drawn from DDR analysis, the benefits of virtual probing are by no means limited to DDR signals.

USB4 Electrical Testing: Where Are We?

Preliminary drafts of the USB4 Compliance Test Specifications (CTS) were released to USB-IF work group members in early 2020 covering the electrical through protocol layer testing of USB4 router assemblies captive cable devices. These CTS documents define the required testing for USB4 hosts, hubs, and peripherals that make up the USB4 ecosystem.  Thunderbolt 3 (TBT3) is also supported in USB4 end products and is tested using the existing TBT3 Host/Device CTS.

While the electrical test methodologies are similar to previous USB 3.2 compliance tests, USB4 is largely based off the TBT3 physical layer, and these test methods have been adopted. Here, we summarize the USB4/TBT3 test approach called out in the aforementioned documents.

USB4 Transmitter Testing

Figure 1. Test points TP2 and TP3 for USB4
Electrical Compliance Testing (Source: USB-IF)

Presently, there is no SIG-TEST software for performing transmitter (Tx) testing, although it is anticipated that one will be released by the USB-IF in the future. All Tx tests performed by QPHY-USB4-TX-RX utilize Teledyne LeCroy methods, with measurements made directly by the oscilloscope.

Figure 1 shows the Test points defined in the CTS for physical layer testing. Testing of the Tx-side is  similar to those performed for USB 3.2 in that the signal is captured at the connector (TP2), where many measurements are defined. Then, a passive cable model is embedded and equalization is applied to result in TP3 measurements.

PCIe Electrical Testing: Where Are We?

Figure 1. PCIe specifications through Rev 5.0.

You may be wondering where we are in the roll out of PCI Express test specifications and active testing. Figure 1 shows the status as of March, 2020.

PCIe 4.0 Transmitter Link-Equalization Testing

Figure 1: Shown is an overview of the PCIe 4.0
link-equalization response test

PCI Express has seen steady, and significant, increases in bit rates in each generational revision. Most recently, bit rates leaped from 8 Gb/s in PCIe 3.0 to 16 Gb/s in the current version 4.0. With these speed increases has come the need for dynamic link equalization, which becomes necessary for the sake of signal integrity. Compliance tests for dynamic link equalization is where things start to get a little more sophisticated, particularly when it comes to PCIe 4.0

PCIe 4.0 Transmitter Electrical Testing (Part II)

Figure 1: With an add-in card as our DUT, we will measure
the transmit signal at the root complex on the system board

With PCIe 4.0 compliance workshops close at hand, let's get familiar with the compliance test process. We've set the stage for electrical transmitter tests by describing the PCIe 4.0 nominal channel and also reviewed the test-equipment requirements; now we'll begin examining the tests in some detail. The two basic transmitter tests are the preset test and signal-quality test.

Gearing Up for PCIe 4.0 Electrical Compliance Test

Figure 1: A key element in PCIe 4.0
compliance test is a high-bandwidth,
real-time oscilloscope (shown is the
Teledyne LeCroy LabMaster 10Zi-A)

Armed with some of the background information and history on PCIe 4.0 electrical compliance testing, we're now ready to look at just what it takes in terms of test equipment to determine compliance for a PCIe 4.0 device. With the increase in data-transfer rate from 8 Gb/s in PCIe 3.0 to 16 Gb/s in PCIe 4.0, so too have the test equipment requirements advanced.

Automotive Ethernet Compliance: Test Equipment Requirements

Figure 1: The TF-ENET-B Ethernet
test fixture offers all necessary
interconnects for compliance test

Having completed an exhaustive tour of the Automotive Ethernet compliance tests, we would be remiss if we didn't offer our take on the test equipment required for the job. Let's look at what the needs would be in terms of the oscilloscope itself as well as the necessary ancillary equipment, test fixture, probes, and cables. We'll conclude with a short discussion of automated compliance software.

The Periodic Table of Oscilloscope Tools: Analyze (Part III)

We're nearing the end of our tour of the Periodic Table of Oscilloscope Tools, our way of presenting our broad palette of oscilloscope tools in a concise, clear fashion. In this installment, we'll finish up the Analyze grouping, by far the largest on the Periodic Table.