Liming Zheng

A new multitime programmable non-volatile memory cell using high voltage NMOS

A new multitime programmable (MTP) non-volatile memory (NVM) cell using high voltage NMOS is proposed. A PMOS transistor is used for programming, erasing, and reading, and a high voltage NMOS is used for selecting the memory cell. The memory cell has fewer number of transistors and terminals compared with the typical conventional memory cell. This reduces the area consumption and simplifies the implementation of memorys external circuit. In addition, the subthreshold swing (SS) of the memory cell is improved for larger coupling ratio. Experimental investigation on transfer characteristics, endurance, retention, and threshold voltage VTH shift and leakage current of the high voltage NMOS of the memory cell are presented. The experimental endurance behaviour of the proposed memory cell is superior to the conventional memory cell.

Investigations on the EFT immunity of microcontrollers with different architectures

Abstract With the development of MCUs and the deterioration of the electromagnetic environment, it has led microcontroller unit (MCU) electromagnetic susceptibility (EMS) to transient burst interference to become the focus on academics and enterprises. Most electromagnetic compatibility (EMC) studies of MCUs have not taken into account the contrasting nature of differing architectures. Subsequently, different MCU architectures may possess varying physical parameters, often resulting in different susceptibility EMI outcomes. This paper shall focus on the relationship between MCU architectures and its EMC susceptibility. Upon close examination, test results have shown to exhibit variances in relation to the two types of MCU architectures with regards to susceptibility of electrical fast transients (EFT) burst. Consequently, the underlying reasons resulting in MCU susceptibility variations based on differing MCU architectures shall also be elaborated on further.

Modelling of initial fast charge loss mechanism for logic embedded non-volatile memories

Abstract An analytical model of the initial fast charge loss mechanism for the logic embedded non-volatile memory (eNVM) is proposed in this paper for the first time. The charge loss phenomenon is caused by the contact-etch-stop-layer (CESL) capacitive effect, which screens part of the charge in the floating gate of the memory cell. Empirical equations are proposed to describe the formation process of the CESL capacitive effect, and the proposed model fits the experimental results excellently including the temperature dependence. The new model will be very helpful for the designers to accurately predict the memorys data retention capability. Furthermore, it can also be used to improve the initial fast charge loss of the logic eNVM.

Cyclic-feature based Doppler scale estimation for orthogonal frequency-division multiplexing (OFDM) signals over doubly selective underwater acoustic channels

Underwater acoustic (UWA) communications enable underwater wireless networks to be applied in various applications, such as oceanographic research, pollution early-warning, disaster prevention, and military systems. However, a major challenge in UWA communications is to combat the Doppler distortion caused by doubly selective (time and frequency selective) channels. Most Doppler scale estimators rely on training data or specially designed packet structures. These methods have fundamental limitations in transmission rate and spectral efficiency. Different from these methods, this paper presents a Doppler scale estimation approach exploiting the redundant information contained within the cyclic prefix (CP) or cyclic suffix (CS) of orthogonal frequency-division multiplexing (OFDM) signals. We analyze the cyclic features of OFDM signals over doubly selective underwater channels in order to demonstrate the relationship between the cyclic features and the Doppler scale. Based on the theoretical analyses, we fin...

A physical model of electron trapping/detrapping in electrically stressed oxide

A physical model of electron trapping/detrapping in electrically stressed oxide has been proposed in this paper. The new model is based on both inelastic multi-phonon trap-assisted tunneling and thermal emission, and also considers the capture effect of oxide bulk traps. It handles every trap separately, and establishes the dynamic procedure of traps capture and emission of electrons. Finally, through the proposed model we may accurately and effectively obtain the filling state of all the oxide traps at any stress and any time, which is very useful for the modeling of the endurance and data retention characteristics of floating gate nonvolatile memories.

Performance evaluation and parameters estimation of the anti-collision protocol used in GB/T 28925-2012

GB/T 28925-2012 is a standard of P. R. China for active radio frequency identification (RFID). It defines wireless communications between reader and tag at 2.45GHz. Framed Slotted Binary Tree (FSBT) anti-collision protocol is adapted in it. However, performance of FSBT is not evaluated and parameters of FSBT are not estimated. A metrics for evaluating time performance and another metrics for evaluating energy performance were proposed with unknown number of tags. They were used to analyze and evaluate the performance as well as help in selecting parameters. Finally, simulation results indicate that this protocol has better performance than previous protocols. Its time metrics can achieve above 1.24, while binary tree is 0.96. Its energy metrics can achieve above 1.39, while dynamic frame slotted ALOHA is 1.09. Its system efficiency can achieve above 47% with unknown number of tags in large scale scenarios.