A Signal Integrity Measuring Methodology in the Extraction of Wide Bandwidth Environmental Coefficients

摘要

In technology tendency, signal integrity performance gets more critical upon today's higher signal transmission speed and quantity demand in every field of applications such as computer CPU and GPU chipset levels, system operation frequency and a variety of communication bus and cable like PCI express, SATA II and AGP bus for computer system. Signal communication speed will shift from 5~10 Gbps range up to ~25Gbps depending on applications. Here we propose a simplified, easy and stable PCB wide bandwidth electrical properties extraction methodology over 20 GHz to evaluate and to measure print circuit board's electrical performance and its variation over environmental parameters, process parameters, like temperature, moisture, thermal cycling and stress. The method is based on the theory of microwave measurement calibration and in-plane stripline mathematical model and integrated with instrument control interface technology. It's using a simple two single-end or two differential pair in different length circuit traces without regular full SOLT, TRL calibration circuits or others disc structures. Measuring these two lines scattering parameters under desired conditions like temperature at this case study, the purely traces insertion loss, characteristic impedance and Dk/Df of constructed material over frequency are extracted.