Simulation Program With Integrated Circuit Emphasis Model Research Articles

SPICE model of MoS2/p-Si photodiode

Molybdenum disulfide (MoS2) 2D-material is considered as one of potential candidates for next generation optoelectronic devices due to its tunable bandgap, relatively high carrier mobility, and good light absorption, etc. From the perspective of circuit simulation and system verification, an equivalent circuit model of MoS2/p-Si photodiode is required. In the paper, the optical response and the carrier transmission process of MoS2/p-Si photodiode are analyzed theoretically. A SPICE (Simulation Program with Integrated Circuit Emphasis) equivalent circuit model of MoS2/p-Si photodiode is proposed, which can be used to simulate the photoelectric characteristics of the 2D device. Based on the established SPICE model of MoS2/p-Si photodiode, the simulation results are consistent with the experimental results of MoS2/p-Si photodiode devices. The trans-impedance amplifier (TIA) is designed for MoS2/p-Si photodiode, and the set-up SPICE model is used to verify the designed TIA circuit. It shows that the SPICE model has potential application for the simulation of the opto-electrical system including the cutting-edge 2-D photo diode.

Design of an ultra‐wideband picosecond pulse generator based on step recovery diodes with an improved SPICE model

SummaryThis article proposed an ultra‐wideband ultra‐short picosecond pulse generator based on step recovery diodes (SRDs). The equivalent circuit model of SRD is analyzed, and an improved nonlinear simulation program with integrated circuit emphasis (SPICE) model is presented for appropriate circuit simulation in Advanced Design System (ADS) software. An external direct current (DC) voltage source is added to bias the SRD. In this article, a conventional shunt SRD topology configuration is developed to generate the Gaussian pulse. According to the measured data, the Gaussian pulse duration for the shunt SRD pulse generator is 210 ps, with the full width at half‐maximum (FWHM) of 110 ps, and the ringing level is −7.8 dB. Moreover, to further improve the tail ringing level, an SRD's mixed topology configuration is introduced and fabricated. The experimental results indicate that the two SRD mixed pulse generator has a pulse duration of 220 ps with FWHM of 120 ps, validating the reasonability of the improved SRD nonlinear SPICE model in ADS. Additionally, there is a considerable improvement in the ringing level of −11.4 dB.

Modeling of Bias-Dependent Effective Velocity and Its Impact on Saturation Transconductance in AlGaN/GaN HEMTs

In this article, we present a surface-potential-based approach to model the bias-dependent effective velocity observed in AlGaN/GaN high-electron-mobility transistors (HEMTs) due to optical phonon scattering. Our model precisely reproduces the progressive decrease in the saturation velocity in GaN HEMTs with increasing gate voltages, as reported in the literature, which is predominantly due to the scattering of electrons, forming the high-density two-dimensional electron gas (2DEG), by optical phonons at high overdrive voltages. We show that this dependence differs from the traditional mobility degradation models in terms of its impact on the device current-voltage (I- V) characteristics and illustrate how the inclusion of a velocity saturation model also provides the model users with an additional handle for parameter extraction. The model is explicit and, by virtue of its Simulation Program with Integrated Circuit Emphasis (SPICE) compatibility, is readily implemented in the industry-standard Advanced SPICE Model for HEMTs (ASM-HEMTs) model and has been validated against experimental dc I-V and RF S-parameter measurements of an in-house GaN device.

Novel Multiple-Layer Stack Capacitor and Its Application in the IRPFA Readout Circuit

In this paper, a kind of four-layer stack capacitor is proposed, which has realized the compatibility with the conventional standard 0.5μm CMOS technology. The effective capacitance per area of the proposed stack capacitor is about three times larger than that of the mono-layer MOS capacitor. The Simulation Program with Integrated Circuit Emphasis (SPICE) model of the presented four-layer stack capacitor has been also established with considering the fringe effect. The results show that the root mean square error of the proposed SPICE model is less than 2%. The model has been applied in the simulation design of the infrared focal plane array readout circuit (IRFPA ROIC) successfully. Based on the improved 0.5μm CMOS process with four-layer stack capacitor, an IRFPA ROIC with 640×512 array has been implemented and the dynamic range is improved from 73db to 78dB.

Methodology to optimize and reduce the total gate area of robust operational transconductance amplifiers by using diamond layout style for MOSFETs

This paper describes a pioneering methodology to design, optimize, and reduce the total gate area of robust Operational Transconductance Amplifiers (OTAs). The Single-Ended Single-Stage (SESS) OTA has been chosen to validate the proposed technique by using the 180 nm planar Complementary Metal-Oxide-Semiconductor (CMOS) Integrated Circuits (ICs) technology. The Electronic Design Automationtool, named iMTGSPICE, was used to design and optimize the SESS OTA. There are several heuristics optimization techniques of Artificial Intelligence to optimize analog and radio-frequency CMOS ICs, but we have selected to use the Genetic Algorithm because it presents the best optimization performance among the other algorithms previously studied. This paper also describes a procedure of converting the Conventional planar MOSFETs (rectangular gate shape) into the Diamond MOSFETs (hexagonal gate shape) with the same electrical performance. Furthermore, it is proposed a procedure to simulate the Diamond MOSFETs (DMs) in the Simulation Program with Integrated Circuit Emphasis (SPICE) because there is still no SPICE model to perform the DM. Additionally, this work proposes a methodology to layout OTAs with Diamond MOSFETs, regarding different values of aspect ratios. The main result of this work reveals a total gate area reduction of approximately 30% of a robust OTA implemented with Diamond MOSFETs, with an alpha angle (α) equal to 45°, with respect to the one observed in the robust OTA implemented with standard MOSFETs, maintaining practically the same electrical performance and robustness.

Technology Computer-Aided Design-Based Simulation Program with Integrated Circuit Emphasis Model for Back-Channel-Etched Thin-Film Transistors with Floating Metal Components.

We report thin-film transistors (TFTs) with floating metal using a back-channel-etched (BCE) process. Since the BCE process reduces the active mask step compared to other processes, it has attracted attention as a back-plane process that could be used for mass production. To realize the long channel in the BCE process, a floating metal is required; this acts as a bridge in the middle of the channel. We used TCAD (Technology computer-aided design) simulations (Atlas 3D) to predict the characteristics of a-Si TFTs with various active layer thicknesses and numbers of floating metal components; simulation results were compared with real measurements. We explain why TFTs do not scale ideally when floating metals are used; this is related to the resistance and thickness of the active channel. If a thick and highly resistive active channel is used, a larger number of floating metals will require greater correction for ideal scaling. Additionally, considering the capacitance between the source metal and channel, the channel influence under the floating metal should be about 89%. We also suggest a new SPICE (Simulation Program with Integrated Circuit Emphasis) model for TFTs with floating metal based on TCAD simulations.

Modeling of organic light emitting structures

The paper has been shown the results of the study of the parameters of organic light-emitting structures based on the SPICE (Simulation Program with Integrated Circuit Emphasis) model studies. A SPICE model of diode structure has been developed, which is implemented in the form of a substitution scheme based on the basic components of the simulator. This model can be extended by introducing additional components of the substitution scheme, which provides higher accuracy in representing the structure specifics. Graphical results of researches of the model of OLED structure at the change of internal parameters have been presented. The obtained data well represent the parameters of real structures and are characterized by a fairly effective adaptation to the experimental data of specific samples.

SPICE Model Identification Technique of a Cheap Thermoelectric Cell Applied to DC/DC Design with MPPT Algorithm for Low-Cost, Low-Power Energy Harvesting

In this work, an identification technique of a simple, measurements-based SPICE (Simulation Program with Integrated Circuit Emphasis) model is presented for small low-cost Peltier cells used in thermoelectric generator (TEG) mode for low-temperature differences. The collection of electric energy from thermal sources is an alternative solution of great interests to the problem of energy supply for low-power portable devices. However, materials with thermoelectric characteristics specifically designed for this purpose are generally expensive and therefore often not usable for low cost and low power applications. For these reasons, in this paper, we studied the possibility of exploiting small Peltier cells in TEG mode and a method to maximize the efficiency of these objects in energy conversion and storage since they are economical, easy to use, and available with different characteristics on the market. The identification of an accurate model is a key aspect for the design of the DC/DC converter, in order to guarantee maximum efficiency. For this purpose, the SPICE model has been validated and used in a design example of a DC/DC converter with maximum power point tracking (MPPT) algorithm with fractional open-circuit voltage. The results showed that it is possible to obtain a maximum power of 309 µW with a Peltier cell 2 × 2 cm at a ΔT of 16 °C and the designed SPICE DC/DC converter performance proved the improvement and optimization value given by the TEG model identification.

Validation of a SPICE Model for High Frequency Electroporation Systems

In this paper, we present an analysis and a validation of a simulation program with integrated circuit emphasis (SPICE) model for a pulse forming circuit of a high frequency electroporation system, which can deliver square-wave sub-microsecond (100–900 ns) electric field pulses. The developed SPICE model is suggested for use in evaluation of transient processes that occur due to high frequency operations in prototype systems. A controlled crowbar circuit was implemented to support a variety of biological loads and to ensure a constant electric pulse rise and fall time during electroporation to be independent of the applied buffer bioimpedance. The SPICE model was validated via a comparison of the simulation and experimental results obtained from the already existing prototype system. The SPICE model results were in good agreement with the experimental results, and the model complexity was found to be sufficient for analysis of transient processes. As result, the proposed SPICE model can be useful for evaluation and compensation of transient processes in sub-microsecond pulsed power set-ups during the development of new prototypes.

Extraction and Analysis of Gamma Irradiated Si BJT SPICE Model

The Simulation Program with Integrated Circuit Emphasis (SPICE) model parameters of pre and post-irradiated silicon bipolar junction transistor (Si BJT) were extracted with the use of Altium Designer (AD)/SPICE model wizard. The percentage changes (Δ%) between forward and reverse-bias parameters of existing BJT (ZETEX BCW72) SPICE model were estimated and also the degradation Δ% between the experimental data of pre and post-irradiated Si BJT were calculated. Then the new measured results by comparison were imported into AD/SPICE model wizard to extracts forward-bias parameters. The extracted forward-bias parameters were used to generate reverse-bias parameters through Δ%. The final extracted Si BJT SPICE model parameters were implemented in SPICE simulator to obtained forward and reverse Gummel plots. As expected, base current (IB) increases, the collector current (IC) increases slightly at low bias base-emitter voltage, leading to current gain degradation due to positive charge trapped in the oxide and interface of the BJT device. In addition, the results of the IB in the forward Gummel flows in parallel with base-emitter junction, while the IB in the reverse Gummel flows across the base-collector junction down to the back side collector contact through the collector region. Finally, the compared results of Si BJT forward Gummel simulation and experimental data showed good agreement.

Impedance measurement front-end based on signal four-phase detection

Internet of Things (IoT), a new direction in information and communication systems, has a significant impact on the development of novel electronics devices. Further progress in the field of IoT devices is conditioned by the development of sensor devices, and in particular, analog front-ends and signal converters for IoT sensors. High sensitivity and wide range applications of IoT sensors can be achieved by methods of impedance spectroscopy. Compared with other methods of physical research, impedance spectroscopy and based on it IoT sensor devices provide ease of implementation, high energy efficiency, good resolution and selectivity. In this paper, we present results of the development and model study of the impedance measuring transducer using the four-phase signal integration method. The implementation of impedance spectroscopy assumes a transition from frequency plots to plots on the complex plane, called as Nyquist plots. The data obtained in this paper are based on the SPICE (Simulation Program with Integrated Circuit Emphasis) model studding methodology, which compares small signal Alternative Current Analysis with large signal Transient Analysis. During the Alternative Current Analysis, Nyquist impedance plot are obtained in the idealized case, and during the Transient Analysis the active ReZ value and reactive ImZ impedance components are calculated for the actual parameters of the measuring transducers and the form of the activating signals. We have proposed a new solution of the impedance measuring transducer based on the four-phase signal commutation and integration method. This method consists in the formation of four informative signals, namely, the voltages $V_{Q1}$, $V_{Q2}$, $V_{Q3}$ та $V_{Q4}$, each of which corresponds to the integration results in the corresponding four phases of the activation signal. In these phases, or time t, the sign functions $A_{Q1}(t)$, $A_{Q2}(t)$, $A_{Q3}(t)$, $A_{Q4}(t)$ of synchronous detections are used: $A_{Q1}(t)=1$ at $t=[0...\pi/2]$; $A_{Q2}(t)=1$ at $t=[\pi/2...\pi]$; $A_{Q3}(t)=1$ at $t=[\pi...3\pi/2]$; $A_{Q4}(t)=1$ at $t=[3\pi/2...2\pi]$. In other time these sign functions are equal 0. Output signals of the impedance measuring transducer, namely, voltages of active $V_{RE}$ and the reactive $V_{IM}$ components are formed by adding and subtracting the numerical values of the above four voltages: $V_{RE}=V_{Q1}+V_{Q2}-V_{Q3}-V_{Q4}$; $V_{IM}=V_{Q1}-V_{Q2}-V_{Q3}+V_{Q4}$. The main units of the impedance measuring analog front-end are a synchronous quadrature detector and an integrator or filter. In comparison to traditional two-phase detection, four-phase detection we have proposed allows avoiding intermediate signal transducing, which provides a significant simplification of impedance measuring transducing. This simplification is achieved by directly integrating the instantaneous value of the $I_{Z}(t)$ current. Important dependences of the measuring transducer output voltages with four-phase integration on the operational amplifiers bandwidth are obtained. Results presented in the article are important for developing a new generation of microelectronic IoT sensor devices based on impedance spectroscopy methods. Main areas of application of such sensor devices are materials science, biochemistry, instrumentation, avionics, ecology, etc.

Technique of increasing the impedance measuring transducers accuracy at inharmoniousness signals

Introduction. Nowadays, one of the most relevant classes of sensor electronics for the Internet of Things is based on the methods of impedance spectroscopy. In general, the informative signals of impedance spectroscopy, namely, an active component or resistance which forms the real part and a reactive component or reactance which forms the imaginary part of complex impedance of the investigated two-terminal network, are formed by specialized analog front-end or measuring transducers. The defining requirements for measuring converters of sensor devices of the Internet Things are their versatility, minimal power consumption, the ability to work at low supply voltages, stability of operation with changing external factors and so on. In this paper, the problem of improving the accuracy of electrical impedance measuring transducers is considered, taking into account the non-harmonic of the driving signals. SPICE model and research technique. The implementation of impedance spectroscopy assumes a transition from frequency plots to plots on the complex plane, called as Nyquist plots. In a number of modern versions of circuit simulation programs the method of impedance analysis is already provided with the use of mathematical functions of Real (Re) and Imagine (Im) components of the signal. Using these functions, it is possible to calculate the corresponding values of the active (Re Z) and the reactive (Im Z) impedance of the object under investigation. As a result of his usage a Nyquist plot is plotted. However, this approach is not universal, and in particular, imposes significant restrictions taking into account the parameters of real signals, namely, their amplitude, shape, non-harmonics, etc. The results obtained in this paper are based on the new SPICE (Simulation Program with Integrated Circuit Emphasis) model studding methodology, which compares small signal Alternative Current Analysis with large signal Transient Analysis. During the Alternative Current Analysis, Nyquist impedance plot are obtained in the idealized case, and during the Transient Analysis the active Re Z value and reactive Im Z impedance components are calculated for the actual parameters of the measuring transducers and the form of the activating signals. The implementation of the above mentioned methodology involves the use of synchronous quadrature detection of the output signals of the measuring circuit. Analysis and correction of results. In accordance with the task of increasing the impedance measuring transducers accuracy at inharmoniousness signals we consider the method of calculating the coefficients KRE and KIM, allowing correcting the measurement results of the active Re Z and the reactive Im Z impedance components. A few analysis and correction results are presented. The obtained regularities can be widely used in correcting the results of impedance spectroscopy upon activation by pulse signals for the vast majority of research options. Conclusion. A new approach is proposed, according to which three arrays of informative signals of active Re Z and reactive Im Z impedance are formed and compared. The first M(AC) array is obtained using small signal Alternative Current Analysis, which corresponds to an idealized version of the measurement transformation and is subsequently used as a reference. The next two arrays M(H1) and M(HN) are obtained by the method of large signal Transient Analysis using the results of integrating the quadrature detector output voltages of the impedance transducer. The array M(H1) is formed when the input source triggers a harmonic oscillation (the first H1 harmonic), and the M(HN) array when activated by a functionally controlled source synthesizes a non-harmonic signal in the form of harmonics HN. The increase in the accuracy of the measurement conversion is provided by coefficients $K_{RE}$ and $K_{IM}$, which allow the correction of the measurement results of the active and reactive components of the impedance. A method for calculating such coefficients and examples of their use are presented.

Simulation of linear dynamic macro model of photo catalytic sensor in SPICE

Purpose – The flow injection analysis (FIA) technique by Yoon-Chang Kim et al. for the determination of chemical oxygen demand (COD) involves the complete analysis including sampling and washing. FIA is analytical method for the measurement of COD using photochemical column. This method uses a bulky setup and takes 10-15 minutes to get the output result which is a tedious and time-consuming job. If conventional method is continuously used for a long time, then it is stable only for 15 days. The purpose of this paper is to propose an approach which is more users friendly and fast in operation by modeling and optimization of sensor used for water quality monitoring. This is to overcome several drawbacks generally found in the previous work like complex designing, nonlinearity and long computation time. The nonlinearity in conventional device is overcome by increasing the values of coefficient of determination R2 which in turn reduce the standard error. Design/methodology/approach – A simulation program with integrated circuit emphasis (SPICE) model of photo catalytic sensor (PCS) is proposed for easy and fast operation and optimization of power. Findings – The proposed macro model operates under subthreshold conditions that are appreciated in large integrated system design. The results of simulation were found to be fairly in agreement with the theoretical predictions. The results exhibited near linear variations of parameters of interest with appreciably reduced response time. The coefficient of determination (R2) has been found to be more in this technique. Research limitations/implications – As the threshold voltage of different photo catalytic materials will be different, Eref in the setup has to be adjusted accordingly to obtain sufficient quantity of current to operate the device. Originality/value – This approach relies on the SPICE model. The development of SPICE model for photochemical sensor is novel which is fast in operation and more user friendly.

SPICE circuit model of voltage excitation fluxgate sensor

A simulation program with integrated circuit emphasis (SPICE) circuit model of voltage excitation fluxgate was proposed. It used the arctangent function to describe the hysteresis loop of fluxgate core, the excitation and measurement coils of the fluxgate were equivalent to a circuit model that contains a kind of non-linear time-varying inductance. Moreover, the expression of non-linear time-varying inductance has been given, which resolved fluxgate modelling itself into solving non-homogeneous ordinary differential equations with variable coefficient, and then the authors used HSPICE to solve the differential equations. The input and output characteristics of the dual-core fluxgate were simulated by this SPICE model. The results show that the model can better simulate the input and output characteristics of actual fluxgate, which verifies the validity of the model.

SPICE modelling of magnetic tunnel junctions written by spin-transfer torque

Spintronics aims at extending the possibility of conventional electronics by using not only the charge of the electron but also its spin. The resulting spintronic devices, combining the front-end complementary metal oxide semiconductor technology of electronics with a magnetic back-end technology, employ magnetic tunnel junctions (MTJs) as core elements. With the intent of simulating a circuit without fabricating it first, a reliable MTJ electrical model which is applicable to the standard SPICE (Simulation Program with Integrated Circuit Emphasis) simulator is required. Since such a model was lacking so far, we present a MTJ SPICE model whose magnetic state is written by using the spin-transfer torque effect. This model has been developed in the C language and validated on the Cadence Virtuoso Platform with a Spectre simulator. Its operation is similar to that of the standard BSIM (Berkeley Short-channel IGFET Model) SPICE model of the MOS transistor and fully compatible with the SPICE electrical simulator. The simulation results obtained using this model have been found in good accord with those theoretical macrospin calculations and results.

A transient SPICE model for dielectric-charging effects in RF MEMS capacitive switches

A transient simulation program with integrated circuit emphasis (SPICE) model for dielectric-charging effects in RF microelectromechanical system (MEMS) capacitive switches was developed and implemented in a popular microwave circuit simulator. In this implementation, the dielectric-charging effects are represented by R-C subcircuits with the subcircuit parameters extracted from directly measured charging and discharging currents in the picoampere range. The resulted model was used to simulate the actuation-voltage shift in switches due to repeated operation and dielectric charging. Agreement was obtained between the simulated and measured actuation-voltage shift under various control waveforms. For RF MEMS capacitive switches that fail mainly due to dielectric charging, the present SPICE model can be used to design control waveforms that can either prolong lifetime or accelerate failure

A SPICE model for thin-film transistors fabricated on grain-enhanced polysilicon film

A simulation program with integrated circuit emphasis (SPICE)-compatible thin-film transistor (TFT) model for TFTs formed on grain-enhanced polysilicon (poly-Si) film by metal-induced-unilateral crystallization (MIUC) is presented. Due to the regularity of grain structures resulting from the MIUC process, the GBs are organized into a manhattan grid. The specific grain boundary (GB) organization allows a physics-based model to be developed. The model is based on the popular BSIM3 submicron CMOS model framework, which captures most of the physical effects in both long channel and short channel down to the submicron dimension. The model has been verified by a large amount of experimental data and shown to be applicable over a wide range of TFT processes with the application of grain-enhancement techniques such as solid-phase crystallization (SPC) and MIUC.

A two-port analogous circuit and SPICE model for Salmon’s family of acoustic horns

A two-port electroacoustic analogous circuit model for finite-length acoustic horns belonging to Salmon’s family of horns is described. The circuit is useful for simulation of horn-loaded electroacoustic systems with electric circuit simulator software such as SPICE (simulation program with integrated circuit emphasis). An implementation of the circuit model for use with the PSpice simulator software is given. Example simulations are presented which illustrate applications of the model.