Phase Delay Instability from Temperature Dependent Glass Matrix Anisotropy in PAM4 Stackups
Temperature-driven phase delay drift in PAM4 stackups stems from the thermal expansion coefficient mismatch between glass fibers and resin matrix.
SPP Test Method
Electrical Characterization
Signal characterization procedures using the short pulse propagation technique provide a measurement of the dielectric constant and the loss tangent at high frequencies. This spp test method involves sending a fast-rising pulse through two transmission lines of different lengths and comparing the received signals. The procedure removes the effects of the connectors and the probe launches to focus on the properties of the material itself, providing a clean set of data that reflects the true performance of the dielectric and the conductor.
It is a preferred approach for characterizing the high-speed substrates used in modern data centers and communications hardware.
Calculating Loss
Calculating the difference in the pulse shapes reveals the frequency-dependent attenuation caused by the resin and the copper roughness. The method is particularly effective for evaluating low-loss materials used in fifth-generation networking and automotive radar systems. Accurate loss data allows designers to predict the reach of high-speed signals and ensure that the energy levels at the receiver are sufficient for error-free operation.
Broadband Capability
Broadband capability of this technique allows for the extraction of material properties from low megahertz ranges up to the millimeter-wave spectrum. The pulse-based approach offers a continuous view of the material behavior, providing more data than resonance-based methods that only measure a single frequency. This data set is used to build accurate models for signal integrity simulation.