Press Release:

Teradyne's New VHDM-HSD™ Interconnect Optimized for Differential Applications

NASHUA, NH, June 8, 1999 -- Teradyne Connection Systems has introduced a new version of its high-performance VHDM interconnect optimized for differential-pair applications. This new variant, called VHDM-HSD (for 'High-Speed Differential'), provides 38 'real' signal pairs per linear inch and shares similar design approaches and materials as the standard 8-row single-ended VHDM connector. Integrated stripline shielding permits 100% of the contacts to be used for signal transmission, thus boosting 'real' signal pin density. The entire VHDM connector platform is modularized to simplify the integration of both styles on the same daughterboard, thus providing a high degree of scalability as performance needs dictate.

VHDM 'HSD' is priced at approximately 18¢ per mated signal contact pair in OEM production volumes; full production is underway now.

VHDM-HSD is particularly well suited for high-speed systems using the new 2.5Gigabits/second device families. Achieving data rates of 2.5 Gb/s and beyond while maintaining low cross-talk levels typically requires 100-ohm differential rather than 50-ohm single-ended connector architectures. Some differential connectors on the market today use radical design techniques that are relatively unproven in real-world applications. By comparison, VHDM-HSD meets data rates of 2.5 Gb/s and cross-talk levels of 3.5% while using widely-accepted design approaches that don't compromise mechanical robustness or reliability.

Other factors impacting electrical interconnect performance include the spacing of the connector's contact pairs and the layout of the PWB hole patterns. VHDM-HSD daughterboard connectors are constructed using a 'wafer' architecture. The wafers are designed with 'close-coupled' pairs for optimized pair spacing through both halves of the connector assembly. This helps minimize the 'in-pair' skew. Stripline shielding integrated into the connector design further improves overall electrical performance and isolation for the contact pairs.

The contact pattern for VHDM-HSD has been arranged for most efficient trace routing on the PWB. Rather than staggering the contact grid, VHDM-HSD uses an orthogonal (in-line) 2mm x 2.25mm pattern that permits trace pairs up to 10 mils wide to be run through the connector without jogs. Routing the signals in such a fashion-and using traces as wide as 10 mils-helps to minimize skin effect losses that could impact high-speed performance. The in-line pattern is achieved by terminating the stripline shields within the linear pin-field rather than on an offset. Additionally, the number of PWB layers needed to route through the connector drops from four to three, helping to improve board cost-effectiveness.

The VHDM connector family is based on a modular architecture, which allows the new differential version of VHDM to co-exist on the same daughtercard assembly with the standard 8-row single-ended version. This permits users to standardize on one connector platform for both single-ended and differential pair requirements, which adds the tremendous value of scalability to your packaging solutions. As density and signal integrity needs dictate, both versions of VHDM can be used interchangeably while maintaining existing power, guidance and grounding modules. The entire VHDM connector family is based upon the widely accepted solderless press-fit approach and includes companion products such as power modules and polarizing/guidance modules. The slot-to-slot pitch for VHDM-HSD connectors is 23mm minimum.

About Teradyne
Teradyne is the world's largest manufacturer of automatic test equipment (ATE) for the electronics industry. Products include systems to test semiconductor devices, printed circuit assemblies, telephone lines, computerized telephone systems, Internet and Intranet networks, and software. The company’s Connection Systems Division is also a leading manufacturer of high-performance interconnects, backplane assemblies, and electromechanical subassemblies used in the production of telecom and Internet equipment. Based in Nashua, New Hampshire, Teradyne Connection Systems also supports customers from regional production facilities in Plano, TX; Milpitas and Fremont, CA; Dublin, Ireland; Mexicali, Mexico, and Grenada.