Samtec Reduces R&D Lab Test Time from Four Hours to Five Minutes

Today’s hyperscale data centers stream terabits of data every second to enable cloud services for global communication. Accelerating the capacity for faster channels pushes the physical limitations of what copper can achieve. Optical fiber can assist long-haul sections of the network, but copper channels are at the core of critical switch fabric and routers. Poorly designed copper interconnects cause bit errors and ultimately crash networks.

Signal aberrations include reflections, skew, crosstalk, dielectric loss, and skin effect loss. Minimizing these anomalies is critical to maintaining properly functioning network channels. Ignoring them will bring a full network down. It is imperative to utilize careful design in conjunction with precise calibration in vector network analyzers (VNAs) with specialized software tools. The Keysight solution Samtec chose reduced this test from four hours to five minutes.

The Key Issues: Faster Data Rates Require New Measurement Techniques

Traditional test and measurement techniques are quickly becoming obsolete. Faster data rates with shorter risetime digital transitions create signal integrity failures inside the data center infrastructure and demand newer measurement science. To characterize a differential channel, traditional four-port VNA measurements require more than four hours of testing for a typical 32-channel connector device-under-test (DUT) assembly. Characterizing this DUT using a four-port VNA entails 64 measurements. By using a 32-port VNA, Samtec obtained all 1,024 S-parameters in a single measurement.

Channel operating margin (COM) is an emerging figure of merit for high-speed digital channel design. The power of COM is that the system designer can trade off component margins as needed to maximize the performance / cost ratio of the complete channel.

By taking crosstalk into account after equalization, the channel designer can optimize overall data throughput using various transmitters and receivers in a design-ofexperiments methodology. This process allows the system designer to make logical design trade-offs to save time and money without sacrificing performance. Modern testing methodologies ensure the rapid bandwidth escalation of today’s terabit networks, enabling the necessary exponential throughput predicted by Moore’s law.

The Solution: 32-Port M9808A PXIe VNA

Samtec engineers employed the Keysight N1930B Physical Layer Test System (PLTS) with a 53 GHz M9808A PXIe VNA, as shown in Figure 1, to achieve their connector performance. No other competitive instrument on the market provides frequency domain, time domain, eye diagrams, multichannel simulation, and W-element modeling in a single test bed platform consisting of 32 ports.

The solution the Samtec engineering team chose uses highly accurate calibration techniques coupled with an intuitive graphical user interface to expedite the test flow. The PXIe VNA produces ultra-stable measurements with high dynamic range, providing accurate test data at very low crosstalk signal levels. Finally, the team needed to use high-frequency measurement ports (53 GHz) to resolve closely spaced impedance discontinuities. It achieved astounding test time savings because of the 32 measurement channels in the PXI-based test platform. Samtec test results provided product data sheets that exemplify industry-leading S-parameter characterization, solidifying its position as a leading component supplier.