Negative Differential Resistance Region Research Articles

The Effect of Temperature on a Single-Electron Transistor I-V Curve

In this paper, the effect of temperature on Single-Electron Transistor (SET) electrical behavior is investigated. In particular, a study of the current-voltage (I-V) curves according to parameter (temperature and gate voltage) variation is presented. Among others, the interesting phenomenon of the N-type negative differential resistance is reported as the temperature increases from absolute zero (0 K) to room temperature. Finally, theoretical analysis and simulation shows that the choice of the appropriate temperature and gate-voltage combination the SET I-V curves demonstrates either a negative differential resistance region, a switching effect, or a simple resistance behavior.

Observation of negative differential Resistance(NDR) in chemically synthesized CuGaSe2 nanorods

CuGaSe2 nanorods has been synthesized through chemical bath deposition method using PVP(polyvinylpyrrolidone) as capping agent. Formation of CuGaSe2 nanorods was confirmed by SEM and TEM analysis. A systematic electrical study has been done on CuGaSe2 nanostructure by changing the Cu to Ga(%) composition ratio from CuSe2 to GaSe nanostructure. I-V characteristics showed that CuGaSe2 nanorods exhibit a negative differential resistance(NDR) region and their peak/valley ratio increases with Ga(%) composition. The occurrence of the NDR region is due to the electron tunneling through the potential barrier of Cu/CuGaSe2 interface. The increase in peak current in NDR region in CuGaSe2 nanorods with the increase in Ga(%) makes them suitable application in building oscillator and memory devices.

Resistive switching transparent SnO2 thin film sensitive to light and humidity

Designing and manufacturing memristor devices with simple and less complicated methods is highly promising for their future development. Here, an Ag/SnO2/FTO(F-SnO2) structure is used through the deposition of the SnO2 layer attained by its sol via the air-brush method on an FTO substrate. This structure was investigated in terms of the memristive characteristics. The negative differential resistance (NDR) effect was observed in environment humidity conditions. In this structure, valance change memory and electrometalization change memory mechanisms cause the current peak in the NDR region by forming an OH− conductive filament. In addition, the photoconductivity effect was found under light illumination and this structure shows the positive photoconductance effect by increasing the conductivity. Memristivity was examined for up to 100 cycles and significant stability was observed as a valuable advantage for neuromorphic computing. Our study conveys a growth mechanism of an optical memristor that is sensitive to light and humidity suitable for sensing applications.

Bidirectional Negative Coupling Induced Dynamical Patterns in a Branched Epoxy-Based Dual-Electrode Microchip Flow Cell

In this contribution, we investigated the spatiotemporal pattern formation of oscillatory electrodissolution of nickel in sulfuric acid with two micro-wires placed in two branches of a microfluidic flow cell. In the flow channel, the reference and counter electrodes are placed at the opposite end of the branched flow channel (contralateral placement). A theory based on modeling the potential drop in the flow channel and the interactions between the reactions showed the presence of bidirectional negative electrical coupling between the electrode potential variables. Experiments and numerical simulations with a kinetic model showed that such bidirectional negative coupling could induce complex dynamics. The experiments showed that anti-phase synchronization occurred only when electrodes were placed in the middle of the branched flow channel. When the electrodes were close to beginning or the end of the channels, where the reference and counter electrodes were placed, respectively, no phase locking was observed. The coupling is intensified in magnitude when the electrodes are in the middle of the flow channel, which maximizes the loop current which can flow towards the reference electrode. The nature of the bidirectional coupling is confirmed in independent experiments with synchrony analysis using the Hilbert transform. Additionally, to further verify the nature of the migration current coupling, a data driven approach, inferring connections of networks (ICON), was utilized. Analysis using the ICON technique showed that the synchronization patterns can be described by a phase repulsive bidirectional coupling. The findings indicate that contralateral placement should be used with great care in electroanalytical application with reactions that exhibit negative differential resistance(NDR) region, e.g., due to passivation or adsorption of an inhibitor. Ultimately, revealing connectivity is essential to characterize the dynamical structures and functions of networks, which in turn, leads to the fundamental understanding of many real-world complex systems such as the topology of the physical or functional connections of neurons in the brain.

Tuning the transport properties of tetracene-based single-molecule junctions with chemical or structural variation of side and anchoring groups.

This study aims to tune the transport properties of tetracene single-molecule junctions with the proper choice and placement of side and anchoring groups. For the operationalization of the molecule that was anchored with thiol or isocyanide groups, two different side groups, amine and nitro, in two different positions, were taken into consideration. For unperturbed tetracene molecule, a prominent negative differential resistance (NDR) feature at 1.8 V was observed with the isocyanide anchoring group while the thiol anchoring group exhibits a plateau region over a bias voltage of 2.2 to 3.2 V. At a bias voltage that is dependent on the chemical or structural change of side or anchoring groups, NDR feature of varying degree was seen in all configurations. Results show that the current flowing through the thiol-anchored molecule perturbed with the amine group at S' position is relatively larger than other configurations because of the smaller HOMO-LUMO gap and broader transmission peaks resulting in a peak to valley current ratio (PVCR) of 1.22. In addition, multiple NDR regions were realized in nitro-perturbed isocyanide-anchored molecule at S position. These results suggest their promising applications in switches, logic cells, and storage devices. The modeling and simulation of side-group mediated anchored tetracene molecule through two electrodic systems were studied using density functional theory (DFT) combined with non-equilibrium Green's function (NEGF) in Virtual NanoLab-AtomistixToolkit (ATK). The electron transport properties were calculated using Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation (GGA) exchange-correlation function. To optimize computing time, gold electrodes were single zeta polarized whereas the molecule, anchor groups, and side groups were double zeta polarized.

Non-uniform superlattice magnetic tunnel junctions

We propose a new class of non-uniform superlattice magnetic tunnel junctions (Nu-SLTJs) with the linear, Gaussian, Lorentzian, and Pöschl–Teller width and height based profiles manifesting a sizable enhancement in the TMR (≈104 − 106%) with a significant suppression in the switching bias (≈9 folds) owing to the physics of broad-band spin filtering. By exploring the negative differential resistance region in the current–voltage characteristics of the various Nu-SLTJs, we predict the Nu-SLTJs offer fastest spin transfer torque switching in the order of a few hundred picoseconds. We self-consistently employ the atomistic non-equilibrium Green’s function formalism coupled with the Landau–Lifshitz–Gilbert–Slonczewski equation to evaluate the device performance of the various Nu-SLTJs. We also present the design of minimal three-barrier Nu-SLTJs having significant TMR (≈104%) and large spin current for the ease of device fabrication. We hope that the class of Nu-SLTJs proposed in this work may lay the bedrock to embark on the exhilarating voyage of exploring various non-uniform superlattices for the next generation of spintronic devices.

InGaAs-based Gunn light emitting diode

We report an n-type In0.53Ga0.47As based Gunn light emitting diode operated at around 1.6 μm. The device structure comprises of an n-type In0.53Ga0.47As epilayer with a thickness of 5 μm grown by Metal Organic Vapour Phase Epitaxy (MOVPE) on a semi-insulating InP substrate and fabricated in a planar architecture with a stepped structure at anode side to suppress the destructive effect of high built-in electric field in propagating Gunn domain. Gunn diode is operated under pulsed voltage with a pulse width of 60 ns and pulse duration of 4.5 ns to keep the duty cycle as low as 0.0013%. The Gunn oscillations with an 1 ns period are observed at around 4.1 kV/cm, which corresponds to the electric field threshold of Negative Differential Resistance (NDR). The light emission at around 1.6 μm also starts at the threshold electric field of the NDR region (E = 4.2 kV/cm) of the current-voltage curve, and the emission intensity increases drastically with increasing applied electric field. The observed light emission at NDR threshold electric field where Gunn oscillations appear on the voltage pulse is attributed to the impact ionisation process occurring in the current domains along the sample, which generates excess carriers to initiate the band-to-band recombination in In0.53Ga0.47As.

Characterization of DC glow discharge plasma in co-axial electrode geometry system by nonlinear dynamical analysis tools

This paper reports plasma behavior in an un-magnetized, co-axial electrode geometry DC glow discharge plasma system. Fluctuations and hysteresis in discharge characteristics have been observed when the electrode system has a central anode configuration. The important fact is that fluctuations and hysteresis in discharge characteristics are not observed in a central cathode configuration. The radial profile of plasma potential shows that it is less than the anode potential, so current continuity is maintained in this current-driven system. This paper also attempts to identify the source of order-to-chaos-to-order in floating potential oscillations with respect to the discharge characteristics. When discharge current (Id) increases after the first negative differential resistance region, the system self-organizes and stabilizes into a state of periodic oscillations. Chaotic behavior is a possible development of new dynamical states in the discharge, which develops from an initial high frequency, low amplitude oscillations (in the range 11.6 mA < Id < 15 mA) and, thereafter, transits to low frequency, large amplitude oscillations at Id >15 mA. In the reverse path of discharge characteristics, the oscillations are more regular than in the forward path. Before the production of low frequency, large amplitude oscillations, the current oscillations follow a similar pattern to the floating potential oscillations. As it transits from chaotic to low frequency, large amplitude floating potential oscillations, discharge current oscillations show a chaotic type of behavior.

Low power highly flexible BiFeO3-based resistive random access memory (RRAM) with the coexistence of negative differential resistance (NDR).

We demonstrated the resistive random access memory characteristics for Cu (top contact)/BFO/PMMA (active layer)/ITO (bottom electrode)/PET sheet as a flexible substrate device configuration. The device showed non-volatile bipolar resistive switching characteristics with good repeatability and the coexistence of NDR for 100 cycles or more with 0.28/3.43 mW power consumption for 1st/100th cycles. The device retains its read state for 104 s or more and switches from LRS to HRS or vice versa for 103 cycles with a pulse width of 100 ms for a write-read-erase-read pulse without affecting the memory characteristics. The Weibull distribution suggests that a set state is more stable than the reset state with shape factor β = 25.20. The device follows Ohmic behavior for the lower applied external field and Child square and Schottky emission for the higher external fields. The Joule heating, Sorets, and Fick's forces are responsible for the formation and rupturing of ionic filament. The coexistence of resistive switching and flexible strength of the device sustains the bending curvature of infinity, 0.2 cm, 1 cm, 1.7 cm, and 2.2 cm. The memory characteristics are retained under tensile conditions for 100 cycles or more. More interestingly, the power consumption for sustaining the NDR region with bending (19 μW) is much lower than without bending (0.19 mW). Thus, this study provides the possibility of integrating BFO with flexible substrates suitable for hybrid organic/inorganic memory structures.

Role of ambient temperature in modulation of behavior of vanadium dioxide volatile memristors and oscillators for neuromorphic applications

Volatile memristors are versatile devices whose operating mechanism is based on an abrupt and volatile change of resistivity. This switching between high and low resistance states is at the base of cutting edge technological implementations such as neural/synaptic devices or random number generators. A detailed understanding of this operating mechanisms is essential prerequisite to exploit the full potentiality of volatile memristors. In this respect, multi-physics device simulations provide a powerful tool to single out material properties and device features that are the keys to achieve desired behaviors. In this paper, we perform 3D electrothermal simulations of volatile memristors based on vanadium dioxide (VO_{2}) to accurately investigate the interplay among Joule effect, heat dissipation and the external temperature T_{0} over their resistive switching mechanism. In particular, we extract from our simulations a simplified model for the effect of T_{0} over the negative differential resistance (NDR) region of such devices. The NDR of VO_{2} devices is pivotal for building VO_{2} oscillators, which have been recently shown to be essential elements of oscillatory neural networks (ONNs). ONNs are innovative neuromorphic circuits that harness oscillators’ phases to compute. Our simulations quantify the impact of T_{0} over figures of merit of VO_{2} oscillator, such as frequency, voltage amplitude and average power per cycle. Our findings shed light over the interlinked thermal and electrical behavior of VO_{2} volatile memristors and oscillators, and provide a roadmap for the development of ONN technology.

Energy Autonomous Two-Way Repeater System for Non-Line-of-Sight Interrogation in Next Generation Wireless Sensor Networks

In this effort, we present a fully energy autonomous two-way repeater system for use in nonline-of-sight (NLOS) interrogation of wireless sensor networks. The proposed system is based on a pair of tunnel diode reflection amplifiers, taking advantage of the existence of a negative differential resistance region that exists when the device is biased at a low voltage in the quantum tunneling region. This enables the development of an ultralow-cost, ultralow-power means to provide amplification. The proposed system demonstrates an ability to extend the total read range of semipassive radio frequency identification (RFID) tags by 4.55 times while consuming over 1000 times less power than comparable technologies, a notable improvement on previously published work. The system shows an ability to be customized to fit a wide array of different applications where NLOS interrogation and the read range of semipassive RFID tags pose a challenge.

Negative-to-Positive Differential Resistance Transition in Ferroelectric FET: Physical Insight and Utilization in Analog Circuits.

In this article, for the first time, we explained a detailed physical insight for negative differential resistance (NDR) to positive differential resistance (PDR) transition in a ferroelectric (FE)-based negative capacitance (NC) FET and also its dependence on the device terminal voltages. Using extensive well-calibrated TCAD simulations, we have investigated this phenomenon on fully depleted silicon on insulator (FDSOI)-NCFET. The NDR-to-PDR transition occurs due to FE layer capacitance changes from a negative to positive state during channel pinchoff. This, in turn, results in a valley point in the output characteristic ( IDS - VDS ) at which the output resistance is infinite. We also found that we could alter the valley point location by modulating the vertical electric field through the FE layer in the channel pinchoff region using body bias ( VBB ). The interface oxide charges also impacted the NDR to PDR transition, and a positive interface charge results in faster NDR to PDR transition. Furthermore, we have utilized the modulation in the NDR-to-PDR transition due to VBB for designing a current mirror. Results show that the output current ( IOUT ) variation due to VDS reduces from ~8% to ~2% with VBB . We have also designed a single-stage common source (CS) amplifier and provided design guidelines to achieve a higher gain in the NDR region. The results obtained using a small-signal model of the FDSOI-NCFET demonstrate that ~25% higher gain can be achieved with the discussed design guidelines in the NDR region compared to the transition region of IDS - VDS . We have also explored the device scaling effect on the amplifier gain and found that ~ 2.23× gain can be increased with smaller channel length and higher device width.

Modulation of electrical performance of zigzag edged tetra-penta-octagonal graphene nanoribbons based devices via boundary passivations

Recently, an sp2 hybridized planar two-dimensional graphene-based carbon allotrope composed of tetra-penta-octagonal rings has attracted considerable interest. The electronic structures and transport properties of zigzag-edged tetra-penta-octagonal-graphene nanoribbons (TPO-ZGNRs) modified via boundary passivation were investigated using density functional theory and the non-equilibrium Green’s function. TPO-ZGNRs were passivated with H, 2H, O, OH, and Cl on the edge to produce TPO-ZGNRs-X (X=H, 2H, O, OH, and Cl). TPO-ZGNRs-H exhibits metallic properties regardless of the nanoribbon width and exists in the non-magnetic state. Although TPO-ZGNRs-OH and TPO-ZGNRs-Cl remain metallic, TPO-ZGNRs-2H and TPO-ZGNRs-O are semiconductors. In addition, the current–voltage curves of three TPO-ZGNRs-X (X=H, OH, and Cl) homojunction device models contain a negative differential resistance region. Notably, the heterojunction device model in which TPO-ZGNRs are passivated with H and O atoms at different edge regions has negative differential resistance and rectification characteristics. This study is expected to facilitate the development of new carbon materials.

Molecular electronics behaviour of L-aspartic acid using symmetrical metal electrodes.

Protein-based electronics is one of the growing areas of bio-nanoelectronics, where novel electronic devices possessing distinctive properties are being fabricated using specific proteins. Furthermore, if the bio-molecule is analysed amidst different electrodes, intriguing properties are elucidated. This research article investigates the electron transport properties of L-aspartic acid (i.e. L-amino acid) bound to symmetrical electrodes of gold, silver, copper, platinum and palladium employing NEGF-DFT approach using self-consistent function. The theoretical work function of different electrodes is calculated using local density approximation and generalized gradient approximation approach. The calculated work function correlates well with the hole tunneling barrier and conductance of the molecular device, which further authenticate the coupling strength between molecule and electrode. Molecule under consideration also exhibits negative differential resistance region and rectification ratio with all the different electrodes, due to its asymmetrical structure. The molecular device using platinum electrodes exhibits the highest peak to valley ratio of 1.38 and rectification ratio of 3.20, at finite bias. The switching characteristics of different molecular device are justified with detailed transmission spectra and MPSH. These results indicate that L-aspartic acid and similar biomolecule can be vital to the growth of Proteotronics.

Two-Terminal Electronic Circuits with Controllable Linear NDR Region and Their Applications

Negative differential resistance (NDR) is inherent in many electronic devices, in which, over a specific voltage range, the current decreases with increasing voltage. Semiconductor structures with NDR have several unique properties that stimulate the search for technological and circuitry solutions in developing new semiconductor devices and circuits experiencing NDR features. This study considers two-terminal NDR electronic circuits based on multiple-output current mirrors, such as cascode, Wilson, and improved Wilson, combined with a field-effect transistor. The undoubted advantages of the proposed electronic circuits are the linearity of the current-voltage characteristics in the NDR region and the ability to regulate the value of negative resistance by changing the number of mirrored current sources. We derive equations for each proposed circuit to calculate the NDR region’s total current and differential resistance. We consider applications of NDR circuits for designing microwave single frequency oscillators and voltage-controlled oscillators. The problem of choosing the optimal oscillator topology is examined. We show that the designed oscillators based on NDR circuits with Wilson and improved Wilson multiple-output current mirrors have high efficiency and extremely low phase noise. For a single frequency oscillator consuming 33.9 mW, the phase noise is −154.6 dBc/Hz at a 100 kHz offset from a 1.310 GHz carrier. The resulting figure of merit is −221.6 dBc/Hz. The implemented oscillator prototype confirms the theoretical achievements.

Key Role for Nonlinear Phenomena of Li-O2 Batteries in Discharge Properties

Li-O2 batteries have attracted much attention as one of the candidates of future energy devices because of their ultimate energy density. This specific property of Li-O2 batteries is derived from the discharging reactions, which consist of the dissolution of Li metal of anode and oxygen reduction reaction (ORR) on the cathode.1-3 However, many issues to apply them for practical use, such as the limited capacity and low energy efficiency, have remained undissolved. In typical Li-O2 batteries, carbon materials are applied as cathodes on which the discharge product, Li2O2, forms and deposits. Due to the inherently low electron conductivity of Li2O2, deposition on the cathode prevents continuous discharge, and causes the cell voltage to drop sharply during constant current discharging. This nonlinear phenomenon, which is called “Sudden cell death”, is known to restrict the discharge capacity of Li-O2 batteries.Herein, we present that the negative differential resistance (NDR), which appears in the ORR of Li-O2 batteries, plays a key role in the discharge properties.4-6 The existence of NDR in the potential region of discharge implies that LiO2, which is an intermediate of the discharge reaction, impedes the ORR and its coverage varies with the cell voltage. Since LiO2 is desorbed from the cathode at higher cell voltage than NDR region, ORR proceeds via “the solution pathway” where Li2O2 forms in the electrolyte is promoted. Meanwhile, the lower cell voltage leads “the surface pathway” in which the adsorbed LiO2 is further reduced to Li2O2 on the cathode surface. Therefore, these results rationally revealed that there is a transition of pathways from the solution to the surface in the galvanostatic discharging process, and this transition causes “Sudden cell death”. The cell voltage where the transition region of reaction pathways appears shifts with cathode materials and electrolytes, therefore, the design of appropriate condition of usage is important to induce the maximum performance of Li-O2 batteries.References1) A. C. Luntz, B. D. McCloskey, Chem. Rev., 114, 11721-11750 (2014).2) C. Shu, J. Wang, J. Long, H. K. Liu, S. X. Dou, Adv. Mater., 31, e1804587 (2019).3) W. J. Kwak, Rosy, D. Sharon, C. Xia, H. Kim, L. R. Johnson, P. G. Bruce, L. F. Nazar, Y. K. Sun, A. A. Frimer, M. Noked, S. A. Freunberger, D. Aurbach, Chem. Rev., 120, 6626-6683 (2020).4) Y. Hase, Y. Komori, T. Kusumoto, T. Harada, J. Seki, T. Shiga, K. Kamiya, S. Nakanishi, Nat. Commun., 10, 596 (2019).5) K. Nishioka, K. Morimoto, T. Kusumoto, T. Harada, Y. Hase, K. Kamiya, S. Nakanishi, Chem. Lett., 48, 562-565 (2019).6) Y. Hase, K. Nishioka, Y. Komori, T. Kusumoto, J. Seki, K. Kamiya, S. Nakanishi, J. Phys. Chem. Lett., 11, 7657-7663 (2020).

Mathematical Modeling of Cyclic Voltammogram Curves of Copper Deposition Involving Multiple Additives

The manufacturing of interconnects and the packaging of integrated circuits are achieved with electrodeposition of copper or other metals. In order to increase the rate of deposition, especially for the large features in packaging, forced convection is provided with certain agitation mechanisms. Although this reduces deposition time, it leads to non-uniform mass transport within each feature and between different features. Special organic additives are used in the solution during the process in order to tune the nucleation and growth of metal, as well as to modify the deposition rate and improve the uniformity. A mathematical model to describe the behavior of organic additives in conjugation with fluid flow and features of various geometry and dimensions is very much desired to facilitate chemistry and process development. In order to achieve this, the physiochemical kinetics of additive and their influence on the Cu deposition rate need to be described precisely.This presentation focuses on a method to extract the kinetic parameters describing the combined effect of multiple additives during copper deposition using rotating disk electrode (RDE). The one-dimensional steady state convection-diffusion equation for each of the chemical species including copper is solved by a semi-analytical method for a range of potentials. The boundary conditions of these differential equations are coupled on the surface of the RDE through the surface coverage of the absorbed species. The steady state of surface coverage of the species represents a dynamic equilibrium of three key processes i.e., adsorption, desorption, and consumption (incorporation). When equilibrium is achieved, the net rate of adsorption and desorption becomes equal to the rate of consumption. At each value of potential, the surface coverage of the additives is solved. At first, the solution is obtained with only one species known as suppressor and it was found that in a specific range of voltage and kinetic parameter multiple solutions of the surface coverage exist at same applied potential. This mathematically explains the S-shaped negative differential resistance (NDR) feature in experimental Cyclic Voltammogram (CV) curves. Figure 1 shows three such experimental S-shaped curves for different concentration of suppressors. The NDR region obtained in the theoretical CV curve is sensitive to the kinetic parameters of the additives. It is possible to match the theoretical and the experimental CV curves by optimizing the kinetic parameters. Determination of the kinetic parameters by particle swarm optimization using experimental data for multiple additive concentration will be discussed in detail in this talk. Figure 1

Negative differential resistance in Si/GaAs tunnel junction formed by single crystalline nanomembrane transfer method

Negative differential resistance (NDR) region was established in Si/GaAs tunnel junction (TJ) formed by single crystalline nanomembrane (NM) transfer method. P + Si NM was transfer-printed onto n + GaAs epi-wafer, leading to the formation of Si/GaAs pn TJ diode comprised of crystalline semiconductors with no biaxial strain. Atomic-scale features at the Si/GaAs junction interface were analyzed by high-resolution transmission-electron-microscopy. The mechanism for NDR phenomenon in the electrical characteristics of Si/GaAs TJ diode was explained by the energy band diagram with a quantum mechanical band-to-band tunneling of carriers. The peak-to-valley-ratio value of TJ diode was 2.32. The results can be applicable to the fabrication of low-power circuits with a combination of lattice-mismatched crystalline semiconductors.

Hybrid Design Using Metal–Oxide– Semiconductor Field-Effect Transistors and Negative-Capacitance Field-Effect Transistors for Analog Circuit Applications

In this work, novel hybrid circuits based on metal–oxide–semiconductor field-effect transistors (MOSFETs) and negative-capacitance field-effect transistors (NC-FETs) were proposed for analog circuit applications, including hybrid operational transconductor amplifier (OTA) and hybrid single-ended to the differential converter. We focus on the design innovation to take advantage of the effect of negative differential resistance (NDR) in NC-FETs. It was found that a significant increase in the output resistance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${R} _{out}$ </tex-math></inline-formula> ) of an OTA can be achieved. Therefore, by setting the quiescent operating point of an OTA in the NDR region of NC-FETs, remarkable improvement in the open-loop gain ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${A} _{OL}$ </tex-math></inline-formula> ), the power supply rejection ratio (PSRR), and the common-mode rejection ratio (CMRR) can be achieved in the proposed hybrid OTA compared with the conventional deep submicron MOSFET-based design. In addition, the hybrid MOSFET–NCFET-based design shows great potential in achieving a highly symmetric differential signal. By employing the NDR effect into the design of a single-ended to differential converter, more symmetric output differential signals can be realized compared with the conventional design. Our findings open new doors for further exploration of hybrid MOSFETs and NC-FETs design in analog circuit applications.

Harmonic Reflection Amplifier for Widespread Backscatter Internet-of-Things

The highly power-efficient backscattering communication scheme holds solid potentials to lead the Internet of Things technologies. However, the asymmetric radio frontend architectures that ensure cheap and pervasive communicating things and tags at one end of the link, overburden the other end of the link (“reader”) with complicated and expensive hardware. This turns out to prevent the integration of the technology in the wide spectrum of consumer electronic devices (e.g. RF smartphone platforms). By separating TX and RX frequency bands, the harmonic backscattering scheme drastically loosens the technological constraints toward integration. We propose here the use of a single tunnel diode to build a harmonic reflection amplifier (HRA), using the nonlinear behavior of the negative differential resistance region to both generate harmonics and amplify the signals. The circuit also behaves like a common backscatter, with the same-frequency backscattering modulation for operation with legacy readers. Operating below 150 mV, the HRA drains 144-μW dc power with a measured positive conversion gain of 18 dB.