Osamu Nagashima

An on-chip clock-adjusting circuit with sub-100-ps resolution for a high-speed DRAM interface

A novel fully digital fine-delay circuit for a high-speed DRAM interface is proposed. The circuit consists of arrayed delay components and generates a group of rail-to-rail delayed signals with sub-100-ps resolution. The input-coupling element (squeezer) in the delay component converges the variations of the resolution. A test device design using 0.35-/spl mu/m technology demonstrates that a resolution of 26 ps can be achieved. A clock-recovery circuit using this circuit has a two-clock-cycle lock time and sub-100-ps error.

A DDR/SDR-compatible SDRAM design with a three-size flexible column redundancy

Two circuit techniques are proposed to design a SDRAM which operates both at a double-data-rate (DDR) and a single-data-rate (SDR). The common/separated I/O scheme enables 2-bit prefetching under a DDR and interrupt operations under an SDR with half the number of data-bus lines otherwise needed. The SSTL/LVTTL-compatible input buffer allows a narrow setup/hold time. Furthermore, the three-size flexible column redundancy enhances the yield. To evaluate these techniques, a 256-Mb SDRAM has been designed assuming 0.16-/spl mu/m technology and simulated with 167-MHz operations.

The charge-share modified precharge-level (CSM) architecture for high-speed and low-power ferroelectric memory

We have proposed the charge-share modified precharge-level architecture with self-timing precharge technique. It is a low-power dissipation architecture for achieving high-density, high-speed, and high-operating-margin simultaneously, making it a leading candidate for use in an Mb-scale ferroelectric memory.