Logic synthesis and circuit modeling of a programmable logic gate based on controlled quenching of series-connected negative differential resistance devices

The circuit concept of programmable logic gates based on the controlled quenching of series-connected negative differential resistance (NDR) devices is introduced, along with the detailed logic synthesis and circuit modeling. At the rising edge of a clocked supply voltage, the NDR devices are quenched in the ascending order of peak currents that can be reordered by the control gates and input gates biases, thus, providing programmable logic functions. The simulated results agree well with the experimental demonstration of the programmable logic gate fabricated by a monolithic integrated resonant tunneling diode/high electron mobility transistor technology.     

Designing Negative Differential Resistance Devices Based on Self‐Heating

There are a number of important emerging applications that would benefit from simple circuit elements that exhibit tunable current‐controlled negative differential resistance (NDR). The advent of such devices would enable, for example, key components for threshold logic and neuromorphic computing such as threshold switches, periodic and chaotic oscillators, and small signal amplifiers. Circuit elements that provide NDR with modifiable electrical characteristics would also be useful for creating optimized “selectors” that enable addressing of individual memory cells in large resistance‐based memory arrays. Currently, there are no simple, bipolar, two‐terminal commercial devices that exhibit current‐controlled NDR. This paper demonstrates that current‐controlled NDR can, in principal, arise from any electrical conduction mechanism that depends superlinearly on temperature, and that in practice a broad spectrum of materials can be utilized to yield NDR. A model is presented that accurately predicts conditions under which NDR can be observed and guidelines are provided for choosing materials that result in desired electrical characteristics. This model accurately predicts the behavior of some existing structures and can be used to tailor future circuit elements for emerging applications. It may also explain the onset of a number of “soft breakdown” phenomena.     

A Programmable Majority Logic Array Using Molecular Scale Electronics

In recent years, many advances have been made in the development of molecular scale electronics which have inspired interest in using the devices thereof for memory and logic. This paper describes the design of a logic architecture using a particular class of molecular devices. Specifically, it is shown that the feature of hysteretic switching common to many molecular devices can be utilized to build programmable arrays. Also utilized in the designs presented here are molecular devices which exhibit negative differential resistance (NDR), a property useful for providing signal restoration at the nanoscale. This work begins by describing the potential for both programmability and NDR in molecular scale electronics. These ideas are then brought together in the design of a programmable logic array based on majority logic.     

Improved vertically stacked Si/SiGe resonant interband tunnel diode pair with small peak voltage shift and unequal peak currents

A vertically integrated and serially connected npnp Si-based resonant interband tunnelling diode (RITD) pair is realised with low temperature molecular beam epitaxy (MBE) by monolithically stacking two RITDs with different spacer thicknesses. The asymmetric design manifests as unequal peak current densities that provide for much larger and uniform separation of the holding states for multi-valued logic. A /spl delta/-doped backwards diode connects the two serially connected RITDs with a very small series resistance. The I-V characteristic of the improved vertically integrated RITDs demonstrates two negative differential resistance (NDR) regions in the forward biasing condition with a small peak shift and unequal peak currents.     

Compact multiple-valued multiplexers using negative differentialresistance devices

Quantum electronic devices with negative differential resistance (NDR) characteristics have been used to design compact multiplexers. These multiplexers may be used either as analog multiplexers where the signal on a single select line selects one out of four analog inputs, or as four-valued logic multiplexers where the select line and the input lines represent one of four quantized signal values and the output line corresponds to the selected input. Any four-valued logic function can be implemented using only four-valued multiplexers (also known as T-gates), and this T-gate uses just 13 devices (transistors) as compared to 44 devices in CMOS. The design of the T-gate was done using a combination of resonant tunneling diodes (RTD's) and heterojunction bipolar transistors (HBT's) with the folded I-V characteristic (NDR characteristic) of the RTD's providing the compact logic implementation and the HBT's providing the gain and isolation. The application of the same design principles to the design of T-gates using other NDR devices such as resonant tunneling hot electron transistors (RHET's) and resonant tunneling bipolar transistors (RTBT's) is also demonstrated     

Novel real-space hot-electron transfer devices

A new class of devices based on hot-electron transfer between two conducting layers is proposed. The essential feature of these devices is a pronounced negative differential resistance (NDR) in the drain circuit, controlled by gate and substrate voltages. This allows a novel type of bistable logic element, which, although being unipolar, is comparable to the CMOS inverter in that a significant current is drawn only during switching. Another possible application is a gate-controlled microwave generator and amplifier. In the present work, the above device concepts are analyzed in the instance of GaAs/ GaAlAs heterojunction realizations.     

基于RTD的新型全加器设计

单双稳态转换逻辑单元(MOBILE)是基于共振隧穿二极管(RTD)电路的一个重要逻辑单元,非常适合阈值逻辑电路设计。由MOBILE可以构成阈值逻辑门(TG)和广义阈值逻辑门(GTG)等阈值逻辑电路。本文通过将三变量异或函数转化为较简单、理想的GTG输入输出函数形式,设计了由GTG构成的新型三变量异或门,并利用该三变量异或门设计了新型的全加器。通过HSPICE仿真和性能比较,该全加器不仅器件数量少,输出延时短,而且能达到较高的工作频率、更小的电路功耗与功耗-延迟积。     

CMOS负阻单元逻辑电路及其发展前景

在回顾了多值逻辑(MVL)电路的优点、分析了共振隧穿器件(RTD)电路的特点和比较了各种类型负阻器件性能的基础上,提出了利用CMOS型负阻单元作为基础性器件设计并实现CMOS型逻辑电路的新概念,并指出了此研究领域的几个重点研究内容和方向。     

Novel multipeak current-voltage characteristics of series-connectednegative differential resistance devices

Three-peak current-voltage (I-V) characteristics can be obtained from the combination of two series-connected negative differential resistance (NDR) devices under certain conditions. We discuss these constraint conditions and demonstrate their role in the design of multipeak I-V characteristics based on NDR devices in series. These phenomena will provide some useful concepts in the multipeak circuit design. Especially, these novel multipeak I-V characteristics can be applied to the multiple-valued logic applications with less devices compared to the traditional structure that stacks N identical devices to obtain N peaks in the I-V curve     

由pnp双极型晶体管和PMOS构成的CMOS负阻单元

使用pnp双极型晶体管和pMOS,按照正反馈产生负阻I-V特性的原理,采用CMOS工艺,设计研制成功CMOS负阻单元,并对它进行了实际的测试与验证,效果良好,而且可以用它作为基础性器件,构成与CMOS工艺相兼容的负阻型逻辑电路,比常规CMOS电路节省大量器件。     

Multiple-input logic circuit design using BiCMOS-based negative differential resistance circuits

We first propose an inverter circuit design using the negative differential resistance (NDR) circuit composed of the standard Si-based n-channel metal-oxide-semiconductor field-effect-transistor (NMOS) and SiGe-based heterojunction bipolar transistor (HBT). By suitably designing the MOS width/length parameters, we can obtain the ??-type NDR current?Cvoltage (I?CV) characteristic. Expanding the inverter circuit operation, the two-input and four-input NOR logic gates are demonstrated. Especially, the design and fabrication of the logic circuit is based on the standard SiGe BiCMOS process. Compared to the traditional NDR device like resonant tunneling diode (RTD), our MOS?CHBT?CNDR-based applications are much easier to be combined with some Si-based or SiGe-based devices on the same chip.     

A comprehensive study of bistable gated bipolar device

Bistable gated bipolar (BGB) devices, a novel negative differential resistance (NDR) device, is investigated in this paper. Experimental demonstration for both n-channel and p-channel devices is carried out in a partially depleted silicon-on-insulator technology. The temperature dependence of its NDR characteristics is measured and found to be in good agreement with analytical models. A feasible scheme is proposed to implement this device in scaled CMOS technologies. As the basic principle for applications, the measured hysteresis characteristic of a storage cell utilizing the BGB device is reported for the first time. Potential applications for logic and memory are also discussed.     

InAs/AlSb/GaSb resonant interband tunneling diodes andAu-on-InAs/AlSb-superlattice Schottky diodes for logic circuits

Integrated resonant interband tunneling (RIT) and Schottky diode structures, based on the InAs/GaSb/AlSb heterostructure system, are demonstrated for the first time. The RIT diodes are advantageous for logic circuits due to the relatively low bias voltages (~100 mV) required to attain peak current densities in the mid-10⁴ A/cm ² range. The use of n-type InAs/AlSb superlattices for the semiconducting side of Schottky barrier devices provides a means for tailoring the barrier height for a given circuit architecture. The monolithically integrated RIT/Schottky structure is suitable for fabrication of a complete diode logic family (AND, OR, XOR, INV)     

Optical logic functions using a tunable wavelength conversion laserdiode

The authors demonstrate optical logic functions of an inverter (NOT) and an exclusive-OR (XOR) using a tunable wavelength conversion (TWC) laser diode developed as a component in optical wavelength division multiplexing (WDM). The TWC laser's optical functions are easily changed by varying bias current settings in gain sections. At just above the turn-on threshold, the TWC laser acts as an optical inverter. At just below the turn-off threshold, it acts as an optical XOR element. The mechanism of both NOT and XOR operations is based on gain quenching accelerated through a saturable absorber, a major feature of the TWC laser. Single longitudinal-mode lasing and the tunability of the lasing wavelength, other features of the TWC laser, are effective in distinguishing lasing light signals from input light signals     

一种全光型光逻辑器件的理论研究

本文提出了光线性传输网络可实现非线性光逻辑功能的概念，从理论上分析了这种逻辑器件的实现原理和性能，并利用Ｙ波导及Ｍａｒｃｈ－Ｚｈｅｎｄｅｒ干涉仪的组合所构成的线性传输网络，实现了ＸＯＲ（异或门）和ＯＲ（或门）的逻辑运算。     

Realization of negative differential resistance and switching devices based on copper phthalocyanine by the control of evaporation rate

We have observed, respectively, a negative differential resistance (NDR) and switching conduction in current–voltage (I–V) characteristics of organic diodes based on copper phthalocyanine (CuPc) film sandwiched between indium-tin-oxide (ITO) and aluminum (Al) by controlling the evaporation rate. The NDR effect is repeatable, which can be well controlled by sweep rate and start voltage, and the switching exhibits write-once-read-many-times (WORM) memory characteristic. The traps in the organic layer and interfacial dipole have been used to explain the NDR effect and switching conduction. This opens up potential applications for CuPc organic semiconductor in low power memory and logic circuits.     

Novel multiple-selected and multiple-valued memory design using negative differential resistance circuits suitable for standard SiGe-based BiCMOS process

A novel multiple-selected and multiple-valued memory (MSMVM) design using the negative differential resistance (NDR) circuits is demonstrated. The NDR circuits are made of Si-based metal-oxide-semiconductor field-effect-transistor (MOS) and SiGe-based heterojunction bipolar transistor (HBT). During suitably designing the parameters and connecting three MOS–HBT–NDR circuits, we can obtain the three-peak current–voltage (I–V) curves with different peak currents in the combined I–V characteristics. For the traditional resonant-tunneling-diode (RTD) memory circuit, one can only obtain four-valued memory states using a constant current source to bias the three-peak NDR circuit. However in this paper, we utilize two switch-controlled current sources to bias the three-peak NDR circuit at different current levels. By controlling the switches on and off alternatively, we can obtain the four-valued, three-valued, two-valued, and one-valued memory levels under the four different conditions. Our design is based on the standard 0.35 μm SiGe BiCMOS process.     

A flexible logic circuit based on a MOS-NDR transistor in standard CMOS technology

A MOS-NDR (negative differential resistance) transistor which is composed of four n-channel metaloxide-semiconductor field effect transistors (nMOSFETs) is fabricated in standard 0.35 μm CMOS technology.This device exhibits NDR similar to conventional NDR devices such as the compound material based RTD (resonant tunneling diode) in current-voltage characteristics.At the same time it can realize a modulation effect by the third terminal.Based on the MOS-NDR transistor,a flexible logic circuit is realized in this work,which can transfer from the NAND gate to the NOR gate by suitably changing the threshold voltage of the MOS-NDR transistor.It turns out that MOSNDR based circuits have the advantages of improved circuit compaction and reduced process complexity due to using the standard IC design and fabrication procedure.     

基于RTD和HEMT的单稳多稳转换逻辑(MML)模拟

用 PSpice对一种由串连的 RTD和 HEMT组成的单稳多稳转换逻辑 (MML)电路进行了模拟。基于自行研制的 RTD的特性曲线提取了合适的器件模型和参数 ,分析了由输入信号调节器件的峰值电流来控制器件翻转次序从而在 MML电路中实现门函数逻辑的原理并由模拟得以证实。     

A novel multiple-valued logic gate using resonant tunneling devices

We demonstrate a novel multiple-valued logic (MVL) gate using series-connected resonant tunneling devices. Logic operation is based on the control of the switching sequence of these devices through the modulation of their peak currents by the input signal. We obtain the literal function, one of fundamental MVL functions, by integrating three InGaAs-based resonant-tunneling diodes with two HEMT's on an InP substrate. The gate configuration is greatly simplified compared with a conventional literal gate employing CMOS circuits