Title
An 8.5-Gb/s/Pin 12-Gb LPDDR5 SDRAM With a Hybrid-Bank Architecture, Low Power, and Speed-Boosting Techniques
Abstract
An 8.5-Gb/s/pin (Gb/s) 12-Gb LPDDR5 SDRAM is implemented in a second-generation 10-nm DRAM process with a hybrid-bank architecture that provides a power-optimized bank solution depending on the bank modes (4B/4BG, 16B-merged bank, 8B-split bank). Based on the specified bank modes, vertical and horizontal skew-cancel schemes for high density and an RBUS-based DBI ac to minimize data transition are newly proposed. Thus, the switching power of RBUS DBI ac is saved by 8.9% compared to that of DBI ac “OFF.” To improve the rank interleaving efficiency with a current increase, partially enabled WCK (PE-WCK) mode is proposed, which minimizes the number of enabled circuits for maintaining the WCK2CK synchronization. Therefore, the current can be saved by 62% without a timing constraint compared to the WCK always-ON mode. To achieve high-speed operation beyond 6.4 Gb/s, speed-boosting techniques, namely, the two-step duty corrector, active resonant load (ARL), and one-tap decision feedback equalizer (DFE) with offset calibration, are newly adopted. In the coarse step in the two-step duty corrector, the value of the duty error decreases to below 5% by suppressing the dc signal. In the fine step, the remaining duty error is further reduced within 2.5 ps by the duty cycle monitor (DCM) and duty cycle adjustor (DCA). Moreover, the skew increase beyond 6.4 Gb/s due to the bandwidth limit by the heavy loading of four-phase WCK signals is alleviated by the ARL, where the four-phase skew is within 5 ps irrespective of process, voltage, and temperature (PVT) variations. The direct feedback DFE enables fast feedback (<; 118 ps) for tap coefficient control, and offset calibration reduces the three-sigma offset of the four dynamic latches in DQ within 5 mV.
Year
DOI
Venue
2021
10.1109/JSSC.2020.3017775
IEEE Journal of Solid-State Circuits
Keywords
DocType
Volume
Active resonant load (ARL),DBI AC,duty cycle adjustor (DCA),duty cycle monitor,hybrid-bank architecture,one-tap DFE with offset calibration,partially enabled WCK (PE-WCK) mode,skew cancel scheme,two-step duty corrector,WCK bias calibration
Journal
56
Issue
ISSN
Citations 
1
0018-9200
0
PageRank 
References 
Authors
0.34
8
28
Name
Order
Citations
PageRank
Chang-Kyo Lee100.34
Hyung-Joon Chi200.68
Jinseok Heo363.05
Jung-Hwan Park400.34
Jin-Hun Jang500.68
DongKeon Lee612.06
Jaehoon Jung717830.12
Donghun Lee822834.37
Dae Hyun Kim950546.95
kihan kim10132.38
Sang-Yun Kim1100.34
Dukha Park1211.05
Youngil Lim1300.68
Geuntae Park1401.01
Seung Jun Lee15168.23
Seungki Hong1600.34
Dae-Hyun Kwon1700.34
Isak Hwang1801.01
Byongwook Na19837.99
Kyung-Ryun Kim2000.34
Seouk-Kyu Choi2100.68
Hye-In Choi2201.35
Hangi-Jung2300.34
Wonil Bae2401.01
Jeong-Don Ihm2500.34
Seung-Jun Bae2600.68
Nam Sung Kim273268225.99
Jung-Bae Lee2810.71