Multi-input Logic Gates Research Articles

N-doped carbon dots: triple mode excitation–emission features for dual channel sensing and logic gate application

Carbon dots (CDs) have congregated massive opportunities in basic and applied research streams owing to their versatile properties. Herein, a unique N-doped CD (NCD) was synthesized via the hydrothermal technique using 3,5-diaminobenzoic acid and hydrazine hydrate as precursors. The NCDs exhibit exceptional optical properties; they emit very different colors under different excitation windows. The fluorescence maxima were at 404 nm (blue), 506 nm (green), and 605 nm (red), respectively, when the excitation wavelengths fall within 300–340 nm, 380–460 nm, and 500–540 nm. The emission features were drastically different from more straightforward CDs (CDBlank) prepared using 3,5-diaminobenzoic acid only via the same hydrothermal route without hydrazine hydrate. We found that the 506 nm and 605 nm emissions originate from various surface states, while the 404 nm emission comes from the NCD core states. The triple emissive NCDs were implemented for sensing; Fe3+ effectively quenches the green and red emissions through turn-off quenching, while ascorbic acid (AA) successfully recovers the quenched emission in a turn-on manner. Both static and dynamic mechanisms were responsible for quenching green and red emissions and were accounted for by complexation-induced aggregation and electron transition from the electron-rich NCDs to the vacant d orbital of Fe3+, respectively. The detection limits for the green and red regions were 7.9 nM and 12.2 nM, respectively. The AA restores both the emission signals by reducing Fe3+ to Fe2+. The calculated detection limits for AA recognition were 0.55 μM and 1.05 μM, respectively, for the green and red emissions. For real-life practicability, some actual samples were examined under the excitation wavelengths (420 nm and 500 nm) with satisfactory outcomes. Furthermore, a multi-input logic gate was constructed to convert the molecular information as fluorescence signal outputs.

Harnessing tipping points for logic operations

We first review ideas of harnessing chaotic attractors to implement robust and flexible logic gates, and recast these concepts in the context of tipping points. The central idea is as follows: The presence of tipping points in complex systems endows it with the capability to switch between very different attractors under small changes in parameter, and this feature can be exploited to obtain reliable logic operations. The binary logic outputs can be efficiently mapped to dynamical attractors bounded in different phase space regions, and the logic inputs can be simply encoded through small changes in a parameter. We then go on to extend our central idea with new implementations of multiple-input logic operations. We show explicitly that the system jumps consistently in response to an external stream of multiple inputs, thus offering robust realizations of more complex multi-input logic gates. We demonstrate that the existence of tipping points offers the advantage that very low-amplitude inputs can yield highly amplified outputs. We also show that noise may play a constructive role, enhancing the reliability of the emergent multi-input logic operations, thus strengthening the concept of generalized Logical Stochastic Resonance. These results indicate that the tipping mechanism can serve to construct general purpose computing devices, which have the added capacity to reconfigure logic functionalities efficiently by small parameter changes.

Eight-Person Voter Implementation Based on Hewlett-Packard Memristor

The logic function based on memristor has been proved and can be applied to the future large scale integrated circuits. In this paper, we use logic circuit based on memristor to realize the function of eight-person voter. The basic logic circuit designed in this paper is consisted of two Hewlett-Packard memristors in series connection and an operational amplifier. Operational amplifiers are used to regulate the output voltages to meet the requirements of the input signals in the next stage circuits. The adder, binary comparator and multi-input logic gate are realized by using the designed logic circuit. Full adders, binary comparators and multi-input logic gates are combined into eight-person voter circuit. Theoretical analysis and spice simulation results verify the feasibility of the circuit under different cases. This method is expected to be applied to more complex voter logic circuits based on memristor.

Switching the activity of Cas12a using guide RNA strand displacement circuits

The CRISPR effector protein Cas12a has been used for a wide variety of applications such as in vivo gene editing and regulation or in vitro DNA sensing. Here, we add programmability to Cas12a-based DNA processing by combining it with strand displacement-based reaction circuits. We first establish a viable strategy for augmenting Cas12a guide RNAs (gRNAs) at their 5′ end and then use such 5′ extensions to construct strand displacement gRNAs (SD gRNAs) that can be activated by single-stranded RNA trigger molecules. These SD gRNAs are further engineered to exhibit a digital and orthogonal response to different trigger RNA inputs—including full length mRNAs—and to function as multi-input logic gates. We also demonstrate that SD gRNAs can be designed to work inside bacterial cells. Using such in vivo SD gRNAs and a DNase inactive version of Cas12a (dCas12a), we demonstrate logic gated transcriptional control of gene expression in E. coli.

Ferromagnetic Resonance Assisted Reconfiguration of Multi-Input Logic Gate Based on Edge Precession Mode

The ferromagnetic resonance (FMR) modes of a multi-input logic gate consisting of Supermalloy-based multiferroic nanomagnets is investigated by micromagnetic simulations and fast-Fourier-transform tools. We propose a clocking scheme to reconfigure the multi-input logic gate by edge-mode resonant excitations based on our numerical micromagnetic simulations. We can reconfigure the input of multi-input logic gate from “000” to “100” by adjusting only the frequency of the resonant excitation, which makes it universal for circuit layout. The miniaturization of the elements is limited. The FMR modes will not work at small dimensions due to the uniform edge modes. By applying a strain along the major axis, we realize the functionality of a multiferroic majority gate. These results may increase programming reliability and provide a guide to multiferroic logic devices applications.

Logic gates realized by nonvolatile GeTe/Sb2Te3 super lattice phase-change memory with a magnetic field input

Nonvolatile memory devices or circuits that can implement both storage and calculation are a crucial requirement for the efficiency improvement of modern computer. In this work, we realize logic functions by using [GeTe/Sb2Te3]n super lattice phase change memory (PCM) cell in which higher threshold voltage is needed for phase change with a magnetic field applied. First, the [GeTe/Sb2Te3]n super lattice cells were fabricated and the R-V curve was measured. Then we designed the logic circuits with the super lattice PCM cell verified by HSPICE simulation and experiments. Seven basic logic functions are first demonstrated in this letter; then several multi-input logic gates are presented. The proposed logic devices offer the advantages of simple structures and low power consumption, indicating that the super lattice PCM has the potential in the future nonvolatile central processing unit design, facilitating the development of massive parallel computing architecture.

A Methodology to Design Spin-Wave-Based Logic Gates in a Single Ferromagnetic Nanostripe Using Spin-Transfer Torque Effects

We present a methodology design of spin-wave-based multi-input logic gates by applying a local spin-polarized current on a single ferromagnetic stripe. Micromagnetic simulation shows that the phase of propagating spin waves in a single ferromagnetic nanostripe can be shifted by $\pi $ /5 without decreasing its amplitude when they pass through an area with nonlinear internal field. The methodology adopting spin-transfer torque effects to fulfill spin-wave-based multi-input logic gates is demonstrated in a single ferromagnetic waveguide. The structure of designed logic gates can be simplified significantly compared with the prototype Mach–Zehnder-type interferometer type gates.

Experimental analysis of multi-lambda injection locking in single mode Fabry–Pérot laser diode

In this paper, we propose multi-lambda injection locking in a single mode Fabry–Pérot laser diode and experimentally analyze its effect on various characteristics of Fabry–Pérot laser diode. We consider mode of the injected beam, number of input injected beams, wavelength detuning, and injected power as important parameters in the analysis of suppression of the dominant mode and hysteresis width. The power required for injection locking is proportional to wavelength detuning, which is one of the important parameters for implementing latching device, switching device, and various other optical devices using single mode Fabry–Pérot laser diode. In multi-lambda injection locking, the amount of power required for the injected beam with and without suppression of self-injected mode plays an important role, and hence, is taken into account in our experiment. The spectrum domain output of three- and four-input NAND gate is shown to verify the concept of multi-lambda injection locking. We observe ON/OFF contrast ratio of more than 40dB when all beams are injection locked, whereas about 1.5dB ON/OFF contrast ratio in all other combinations of input beam injection. The analysis of multi-lambda injection locking can be used for multi-input optical devices such as multi-input logic gates, latches, and switches.

Power·delay product in COSMOS logic circuits

In this simulation work, we use COSMOS logic devices—a novel single gate CMOS architecture recently announced [1]—in multi-input logic gates, assessing its performance in terms of power·delay product. We consider three different multi-input logic circuits: a two-input NOR gate, a three-input NOR gate, and a three-input composite NOR/NAND (NORAND) gate. For this power·delay analysis, the transient TCAD simulations are employed in a mixed-mode approach where circuit and device simulations are coupled together, culminating in the delay response of the circuits as well as the static/dynamic current components. The analysis shows that all circuits, except the 3-input NOR gate, has acceptable characteristics at low-power applications and static leakage limits all COSMOS circuits at high-bias conditions.

Ultrafast WDM logic

Ultrafast all-optical logic gates that accept optical inputs in which wavelength designates bit position within the overall byte are proposed and demonstrated. Four-wave mixing is shown to provide a conditional test function that can be used to construct any multi-input logic gate. Polarization provides the logic state for each bit. Implementations that use semiconductor optical amplifiers as the four-wave mixing medium can be monolithic and compact.

Resonant tunnelling hot electron transistors: present status and future prospects

We proposed and demonstrated a resonant-tunnelling hot electron transistor (RHET) in 1985, and developed a multi-emitter RHET in 1993, enabling us to make an SRAM cell and multi-input logic gates using a single transistor. Through the development of these quantum tunnelling transistors, we have created the technology needed to fabricate precisely controlled quantum well structures, and have mostly understood the physics behind quantum well structures. Although this technology has been successfully used to develop heterostructure transistors and quantum well laser diodes, RHETs cannot yet be used in practical applications. One reason is that the RHET should be cooled down to about 77 K and its functionality is insufficient to replace conventional semiconductor devices. To make these RHETs practical for future use in cryoelectronic systems, integration with complementary-HEMT logic circuits or developement of new architecture circuits will be essential. There are also other important areas of research for us. One is to develop room temperature quantum functional bipolar transistors. Another is to develop quantum box devices based on the RHET technology, searching ultrasmall limit of electron devices. These research will be also useful in the development of photonic devices, such as quantum dot lasers and new photonic memory devices.

Characterization of heterostructure complementary MISFET circuits employing the new gate current model

A complementary logic circuit employing heterostructure MISFET's is shown to have a larger logic swing and noise margin than an E/D MESFET logic circuit. The noise margin is calculated using a new gate current model that is derived by taking into account the small surface potential dependence on the gate voltage at the heterointerface. The circuit simulation indicates that, for multi-input logic gates, a NAND gate configuration is superior to a NOR gate configuration from the viewpoints of noise margin and switching speed. The normalized high- and low-level noise margins are comparatively balanced (34 and 49 percent) for a three-input NAND gate. For a fan-in/fan-out of 3/3 and a 100-fF wiring capacitance condition, a 54-ps delay time and 57-μW power dissipation/gate at a 100-MHz clock frequency are possible for a NAND gate with 0.5-μm gate-length MISFET's at 77 K.