A 0.8 – 2.4 Gbps Driver With Adjustable De-Emphasis Scheme For Ddr3 Memory Interface

The need for greater memory bandwidth to boost the computer system performance has driven system memory evolution to Double Data Rate Synchronous Dynamic Read Access Memory (DDR SDRAM) technologies. Trends to maximize memory bandwidth have caused Inter-Symbol Interference (ISI) become significant which degraded the signal integrity of transmitted data. In this research, a driver architecture with adjustable de-emphasis and impedance control scheme is proposed for high-data rate and high-density DDR3 SDRAM memory system. The proposed driver is implemented using 45 nm CMOS process technology. The designs and implementations of the proposed driver involve the design of driver architecture, data controller, impedance calibration block with reference generator as well as the layout for critical analog circuits i.e. three driver segments for post-layout simulations to ensure the parasitic in layout does not has significant effect on driver performances. The driver has 15 de-emphasis legs that can form 15 de-emphasis voltage levels that capable of reducing ISI-induced jitter at high operating frequency. Moreover, high density DDR3 memory system can deteriorate the far-end eye jitter and eye height that causes difficulties in data sampling and recovery. Thus, the driving impedance of the proposed driver can be programmed between 20, 30 and 40 Ω to compensate the variability of board routing effect in memory system and hence, improving signal integrity

Top quark spin and HtbHtb interaction in charged Higgs and top quark associated production at LHC

We study the charged Higgs production at LHC via its associated production with top quark. The kinematic cuts are optimized to suppress the background processes so that the reconstruction of the charged Higgs and top quark is possible. The angular distributions with respect to top quark spin are explored to study the $Htb$ interaction at LHC.Comment: 10 pages,5 figures, to appear in PR

Lepton flavor violating signals of the neutral top-pion in future lepton colliders

The presence of the top-pions $\pi_{t}^{0,\pm}$ in the low-energy spectrum is an inevitable feature of the topcolor scenario. Taking into account the constraints of the present experimental limit of the lepton flavor violating($LFV$) process $\mu\to e\gamma$ on the free parameters of topcolor-assisted techicolor(TC2) models, we study the contributions of the neutral top-pion $\pi^{0}_{t}$ to the $LFV$ processes $\mu^{+}\mu^{-}\to\tau \mu$ (or $\tau e$), $\gamma \gamma\to\tau \mu$ (or $\tau e$), $e^{+} e^{-}\to\tau \mu$, and $e \gamma\to e \pi_{t}^{0}\to e \tau \mu(e)$ via the flavor changing ($FC$) couplings $\pi_{t}^{0}l_{i}l_{j}$ and discuss the possibility of searching for the $LFV$ signals via these processes in future lepton colliders.Comment: References added, some typos corrected. Version to be published in Phys. Rev.

Associated production of the top-pions and single top at hadron colliders

In the context of topcolor assisted technicolor(TC2) models, we study the production of the top-pions $\pi_{t}^{0,\pm}$ with single top quark via the processes $p\bar{p} \to t\pi_{t}^{0}+X$ and $p\bar{p} \to t\pi_{t}^{\pm}+X$, and discuss the possibility of detecting these new particles at Tevatron and LHC. We find that it is very difficult to observe the signals of these particles via these processes at Tevatron, while the neutral and charged top-pions $\pi_{t}^{0}$ and $\pi_{t}^{\pm}$ can be detecting via considering the same sign top pair $tt\bar{c}$ event and the $tt\bar{b}$ (or $t\bar{t}b$) event at LHC, respectively.Comment: latex files,14 pages, 7 figures. Accepted for publication in Phys. Rev.