A 1.1-V 10-nm Class 6.4-Gb/s/Pin 16-Gb DDR5 SDRAM With a Phase Rotator-ILO DLL, High-Speed SerDes, and DFE/FFE Equalization Scheme for Rx/Tx

• Published in: IEEE journal of solid-state circuits 2020-01, Vol.55 (1), p.167-177
• Main Authors: Kim, Dongkyun, Park, Minsu, Jang, Sungchun, Song, Jun-Yong, Chi, Hankyu, Choi, Geunho, Choi, Sunmyung, Kim, Changhyun, Han, Minsik, Koo, Kibong, Kim, Yongmi, Lee, Dong Uk, Lee, Jaein, Kwon, Kihun, Choi, Byeongchan, Kim, Hongjung, Ku, Sanghyun, Kim, Jongsam, Oh, Seungwook, Im, Dain, Lee, Yongsung, Park, Mingyu, Choi, Jonghyuck, Chun, Junhyun, Jin, Kyowon
• Format: Article
• Language: English
• Subjects: Circuits; Clocks; CMOS; DDR5; DDR5 decision feedback equalization (DFE); Decision feedback equalizers; Delays; DIMM; DRAM; DRAM interface; Equalization; feedforward equalization (FFE); High speed; on-die termination (ODT); Performance enhancement; phase rotator (PR) delay locked loop (DLL); Pins; Power consumption; Power efficiency; SDRAM; Training; Vibration; write-level training
• ISSN: 0018-9200; 1558-173X
• DOI: 10.1109/JSSC.2019.2948806

A 1.1-V 6.4-Gb/s/pin 16-Gbit DDR5 is presented in 10-nm class CMOS technology. Various functions and circuits' techniques are newly adopted to improve performance and power consumption compared with DDR4 SDRAM. First, to realize two times higher speed than DDR4, the injection-locked oscillator (ILO) delay locked loop (DLL) is adopted for the low jitter high-speed performance. The proposed DLL with phase rotator (PR) and ILO allows to minimize the clock tree of DRAM, lowering skew and jitter in the DRAM internal clock path. Second, for the high-speed write operation, DQS gate opening control and write leveling are very important to minimize the turnaround time of DRAM, and thus new sequence and logic for the write-level training are introduced in this article. Third, to maximize the data valid window of read DQs, duty cycle adjustable serialize circuit methods are proposed. Finally, to improve the interface speed, the decision feedback equalization (DFE) and feedforward equalization (FFE) are adopted to Rx and Tx, respectively. By implementing all the items mentioned earlier, the 1.1-V 6.4-Gb/s/pin 16-Gbit DDR5 achieved 6.4-Gb/s/pin performance at 1.05-V V DD , with its power bandwidth efficiency 30% higher than that of DDR4.