Package electrical specifications for giga bit signaling I/Os

Abstract

Giga bit per second (Gb/s) signaling is rapidly proliferating in computing, networking and telecommunication systems. Giga bit signaling uses differential circuits for transmitter (TX) and receiver (RX) circuits. Often industry standards define system level performance metrics. Specifications for the majority of components, such as the package interconnect are not specified. At the Gh/s speeds. the package performance is a significant conttihutor to the system performance, and must he carefully specified to balance performance, cost, and manufacturing capability. The results of this work can he used to defme the package performance target using scattering (S) parameters in the frequency domain for design engineering. This specification can he used as a proxy for the package models in the overall cbannel between a pair of TX and RX. Then, the time domain analysis of the channel can provide system level performance metrics such as eye opening and jitter. This paper describes a methodology to specify the S parameters for a desirable level of performance in time domain. These specifications are normalized and scale with the speed of the input-output (VO) interface. Several examples are shown to show the trade off between the frequency domain performance and the impact on the time domain.