Electrical properties of dielectric substrate are critical in designing high-speed products in terms of signal and power integrity. It is important to accurately characterize the dielectric properties to avoid overestimating or underestimating in the design. This paper proposes the improved “Root-Omega” method for extracting dielectric properties from fabricated multilayer printed circuit boards. Based on the electrical properties of fabricated transmission lines, the improved “Root-Omega” method applied to cases with smooth and rough conductors is validated using simulations. Error sensitivity analysis is performed to demonstrate the potential errors in the original “Root-Omega” procedure and the error sensitivity is significantly reduced by the proposed improvements.

Improved “Root-Omega” Method for Transmission-Line-Based Material Property Extraction for Multilayer PCBs

Method and test device for performing testing in a network conveying a plurality of traffic flows. At the test device, receiving traffic flows through a first interface of the test device on a first segment and forwarding the received plurality of traffic flows towards a second segment of the network through a second interface. At the test device, receiving a test request directed to an address of a test module and, in response to the test request, causing a sequence of proprietary traffic to be injected on the second segment. A reprogrammable test device comprising a networked test module at least in part on a reprogrammable partition of a programmable logic device and a reprogramming module, on a static partition of the programmable logic device, for reprogramming at least a portion of the reprogrammable partition implementing the test module in accordance with reprogramming data received at the test device.

Pass-through test device

Far-end crosstalk (FEXT) noise is a critical factor that affects signal integrity performance in high-speed systems. The FEXT level is sensitive to the dielectric inhomogeneity of the stripline in fabricated printed circuit boards (PCB). Stripline is typically modeled as a 2-layer model with core and prepreg layers. However, in reality, the stripline is laminated by multiple inhomogeneous dielectric layers (IDL). The dielectric layers of the stripline are laminated with epoxy resin and glass bundles. The dielectric permittivity (e r ) of the epoxy resin and glass bundles are different, which causes the inhomogeneity of the dielectric layers while also increasing the FEXT magnitude. Therefore, a typical 2-layer structure is inaccurate to model the FEXT. In this paper, the stripline model is constructed with the core, prepreg, and resin pocket layers. To analyze the stripline with three IDL, a practical superposition method is proposed. A design guideline to mitigate the FEXT level in the stripline design is proposed based on the method.

Far-End Crosstalk Analysis for Stripline with Inhomogeneous Dielectric Layers (IDL)

Skew is unintentionally introduced within a differential pair, through misalignment of conductors and glass fiber bundles in Printed Circuit Board (PCB) dielectric layers. Manufacturers do not control interposition of specific glass bundles to supplied board design (artwork). Therefore, an unknown and random factor is added to each produced PCB. Current paper describes a method that utilizes a set of measurements and numerical models to estimate worst-case skew for the aforementioned effect. First, test vehicles are built, and then cross-sections are analyzed with Scanning Electron Microscope (SEM) for precise measurements. Numerical models are constructed to correlate with real DUT; after correlation is achieved, relative location of conductors to glass bundles is swept to obtain best and worst case skew.

Measurement and correlation-based methodology for estimating worst-case skew due to glass weave effect

The present disclosure relates to small form factor pluggable units (SFP) having a monitoring probe. The monitoring probe is capable of monitoring a signal received by the SFP unit, in order to analyze the received signal and to generate a status signal. The monitoring probe may monitor a received signal directly or a copy thereof. The monitoring probe may be non-intrusive of the received signal, or intrusive. The monitoring probe may further generate a diagnostic of the received signal.

Small form factor pluggable unit with signal monitoring capabilities

Numerical method is used to investigate the glass weave effects on via coupling and trace transmission properties. Studies indicate that a simple two-dimensional periodic structure is accurate enough for via coupling simulations while more complicated three-dimensional glass-weave structures have to be used for studies of trace transmission properties. Analytical formulas are provided to estimate the first resonant frequency of the glass weaves. The impact of trace-glass-weave orientations on resonances of traces has been investigated for both single-ended and differential striplines. It has been demonstrated that statistical Gaussian distribution of pitch sizes due to fabrication tolerance and the dielectric losses can reduce the glass-weave effects. The studies here are useful for better understanding of the high-frequency signal integrity performance of printed circuit boards.

Numerical Investigation of Glass-Weave Effects on High-Speed Interconnects in Printed Circuit Board

Various example embodiments are disclosed. According to one example embodiment, a small form factor pluggable (SFP or SFP+) module may include an equalizer and a logic controller. The equalizer may be configured to receive data, provide signal information to a logic controller based on the received data, equalize the data based on equalization instructions received from the logic controller, and transmit the equalized data. The logic controller may be configured to transmit the signal information received from the equalizer receive programming instructions provide the equalization instructions to the equalizer based on the programming instructions, receive control inputs associated with the data, and provide status outputs based on the control inputs and the programming instructions. The SFP or SFP+ module may be configured to plug into a small form factor (SFF) host connector.

Richard R. Brooks

Papers

Numerical Investigation of Glass-Weave Effects on High-Speed Interconnects in Printed Circuit Board

Programmable sfp or sfp+ module