Dong-seok Kang

A 40nm 2Gb 7Gb/s/pin GDDR5 SDRAM with a programmable DQ ordering crosstalk equalizer and adjustable clock-tracking BW

Most DRAM interfaces such as GDDR5 and DDR3 use parallel single-ended signaling due to pin-count restriction and backward compatibility. Notwithstanding poor signal and power integrity issues, GDDR5 speed reached beyond 5Gb/s in recent years by utilizing data bus inversion, error-detection coding, data training and channel equalization [1–3]. However, channel crosstalk is becoming a major barrier to further speed improvement. A common solution for channel crosstalk reduction at the system level is to use a shielding line or wide spacing between signal lines, but increasing the number of layers in a chip package and PCB increase system cost. To remove the shielding lines and increase speed, this paper presents a channel crosstalk equalizer with programmable signal ordering capability for the DRAM transmitter. In addition, this paper addresses tri-mode clocking to reduce the system jitter for better timing margin: PLL off, LC-PLL and injection-locked oscillator.

Construction of a Knowledge Base for Ergonomic Design with Human Models

In order to economically evaluate products and workplaces from the early stage of design, it is essential to provide the designer with a variety of design and evaluation means. In Korea, incorporation of ergonomic design and evaluation into the computer-aided design process of product development in industry has been in great need. A number of ergonomic design models have been developed and are currently in use. Evaluation functions embedded in those models are, however, based mostly on predictive algorithms such as reach and visibility tests, whereas numerous ergonomic guidelines which constitute a major part of design knowledge have been rarely accommodated to such models. In this research, a knowledge base was constructed to expand the scope of ergonomic evaluation being made through those models. First, a new framework based on an object-oriented database for the model was suggested from the developers standpoint. Second, the knowledge modeling was done based on the definition through the object-oriented database. Finally, the knowledge base was implemented in the prototype design model that enables to evaluate design alternatives, interactively. It is expected that the knowledge base proposed would lessen the burden of designers through efficient evaluations from the early stage of design.