Jung Sunwoo

A 20nm 1.8V 8Gb PRAM with 40MB/s program bandwidth

Phase-change random access memory (PRAM) is considered as one of the most promising candidates for future memories because of its good scalability and cost-effectiveness [1]. Besides implementations with standard interfaces like NOR flash or LPDDR2-NVM, application-oriented approaches using PRAM as main-memory or storage-class memory have been researched [2-3]. These studies suggest that noticeable merits can be achieved by using PRAM in improving power consumption, system cost, etc. However, relatively low chip density and insufficient write bandwidth of PRAMs are obstacles to better system performance. In this paper, we present an 8Gb PRAM with 40MB/s write bandwidth featuring 8Mb sub-array core architecture with 20nm diode-switched PRAM cells [4]. When an external high voltage is applied, the write bandwidth can be extended as high as 133MB/s.

A 58nm 1.8V 1Gb PRAM with 6.4MB/s program BW

In mobile systems, the demand for the energy saving continues to require a low power memory sub-system. During the last decade, the floating-gate flash memory has been an indispensable low power memory solution. However, NOR flash memory has begun to show difficulties in scaling due to the devices reliability and yield issues. Over the past few years, phase-change random access memory (PRAM) has emerged as an alternative non-volatile memory (NVM) owing to its promising scalability and low cost process [1,2]. In this paper, a PRAM, implemented in a 58nm PRAM process with a low power double-data-rate nonvolatile memory (LPDDR2-N) interface, is presented [3].

A 20-gb/s 256-mb DRAM with an inductorless quadrature PLL and a cascaded pre-emphasis transmitter

A 20GB/s 1.8V 256MB DRAM is designed and fabricated using an 80nm CMOS process. An inductorless tetrahedral oscillator generates inherent quadrant phases combined with a cascaded pre-emphasis transmitter to achieve a 10Gbit/s/pin data rate.

An 8 Gb/s/pin 9.6 ns Row-Cycle 288 Mb Deca-Data Rate SDRAM With an I/O Error Detection Scheme

This paper proposes a deca-data rate clocking scheme and relevant I/O circuit techniques for a multi-Gb/s/pin memory interface. A deca-data rate scheme transmits 10 bits in one external clock cycle to transfer an error control code along with original data seamlessly without a timing bubble. A 288 Mb SDRAM has been designed using the proposed scheme combined with fast cycling core techniques to have both high I/O bandwidth and fast random cycling. Measured results show that the chip exhibits per-pin data rate of 8 Gb/s and row cycle time of 9.6 ns

BER Measurement of a 5.8-Gb/s/pin Unidirectional Differential I/O for DRAM Application With DIMM Channel

A 1-Gbit DRAM with 5.8-Gb/s/pin unidirectional differential I/Os was implemented by 70 nm DRAM process and a main memory module with dual in-line memory module was assembled. The implemented DRAM chips have control methods for core noise injection and a cyclic redundancy check (CRC) generator for outer-data inner-command architecture. Measurements for bit error rate and jitter performance of the transmitter was performed on an electrical test board which emulates the real memory systems environment. Also, the effect on power noise was analyzed from the DRAM chips with three class values of power decoupling capacitance for the peripheral part. The results show that no additional coding for the differential I/O protection in DRAM, like CRC, is required up to 5.8-Gb/s/pin operation.

Channel BER Measurement for a 5.8Gb/s/pin unidirectional differential I/O for DRAM application

A 5.8 Gb/s/pin DRAM with unidirectional differential I/Os and 1 Gbit memory core was designed and 23.2 GB/s memory module was assembled. Tx BER measurement on an electrical test board similar to real memory sub-systempsilas environment was performed and the results show that no additional coding for the differential I/O protection, like CRC, seems to be required up to 5.8 Gb/s/pin operation. Also, an efficient timing usage method using matched path for a possible implementation of CRC computation in ODIC architecture was proposed.

A 800Mb/s/pin 2GB DDR2 SDRAM using an 80nm triple metal technology

A 1.8V, 800Mbit/s/pin, 2GB DDR2 SDRAM is developed using an 80nm triple metal technology. With the triple metal technology, NMOS precharge I/O scheme and statistical analysis, DDR800 4-4-4 performance is achieved at 1.8V. For mass production, a high-speed clock using an on chip PLL and an address-pin-reduction mode are employed.