An algorithm is proposed to implement digital peeling to determine dominant time constants of an exponential transient process. The method is simpler to implement and reduces computational time to a large extent in comparison to other techniques widely used. Apart from a synthetic test function, the algorithm has been implemented on reported experimental transient decay curves of Cs 2HfCl 6 (CHC) single crystal scintillation to verify its efficacy. Finally, drain current detrapping transients of unpassivated AlGaN/GaN high electron mobility transistors (HEMTs) are analysed to determine the trap energy levels and concentrations. The validation of this digital peeling technique is also carried out by comparing with conventional method of time constant extraction from HEMT current transients. The extracted exponentials from the transient data efficiently fits well with the experimental data and can be extensively used for transient analysis. The digital peeling technique has wide applicability and can be used to analyze all exponential processes which occur in all domains of science.
The development of SAW transducers requires a series of steps ranging from material selection, geometry design, as well as, the selection of fabrication techniques for their characterization and validation process. Here, we use the finite element method in COMSOL Multiphysics to present a methodology and a detailed analysis of the design of a SAW transducer in a delay line configuration. First, we simulate single-finger and double-finger configurations of IDTs on LiNbO3 in 64°YX and LiNbO3 128°YX orientation, with the objective of 1) comparing the simulation results with the analytical delta model to validate the simulation process, presenting Pearson correlation values ranging from 0. 76 to 0.84. 2) calculate a maximum frequency value obtainable for those configurations from a resolution of 5 microns in the photolithography technique, used for the fabrication of SAW transducers. Next, we extended the analysis to study a specific transducer design made to operate at a resonant frequency of 97 MHz. In order to determine the influence of piezoelectric material and IDT configuration we compared identical designs on 128°YX and 64°YX orientations of LiNbO3 with single and double finger configurations and adding the SPUDT configuration. We observed the best results for the single-finger IDT configuration in 128°YX LiNbO3 orientation compared to the other variants through its insertion loss level of -7.29 dB, its average sidelobe level of 18.63 dB, and its average transition band slope for the main lobe of 119.59 dB/MHz. The results obtained can serve as a guide for new researchers or students to expand the use of numerical tools in the design of SAW transducers and SAW devices.
In this paper, we design and simulate single ended Colpitts Oscillator (CO) in integer and fractional order domains. The oscillators are realized in 32 nm node conventional MOSFET and carbon nanotube field effect transistors (CNTFET) technologies. Therefore, four COs have been designed, simulated and rigorously compared. These include integer order conventional MOSFET based CO, fractional order MOSFET based CO, CNTFET based integer order CO and CNTFET based fractional order CO, all based on 32 nm technology nodes. The fractional order approach has been used as it results in better control over the phase and frequency of the oscillator. Herein fractional order capacitors of various orders, used in realizing the fractional order COs, are realized and their frequency responses are studied. This is being done to ensure whether the designed pseudo-capacitances have fractional behavior or not in the desired frequency and phase spectrum. It has been observed that the variation of fractional order (α) from 0.4 to 0.81 has resulted in a slight reduction of oscillation frequency from 1.68GHz (α=0.4) to 1.351GHz (α=0.81) keeping the pseudo-capacitance same at 0.3nF in MOS based topology. Further, CNTFET based integer order as well as fractional order COs have been designed to address the power consumption and the complexity issues of the fractional order COs. The CNTFET based fractional order CO retains the advantages of fractional order domain as well as power efficiency of CNTFETs. Furthermore, it has been observed that integrating fractional order capacitor (FOC) with the CNTFET CO results in much larger constant phase zone (CPZ), an important performance measuring parameter. A rigorous comparative analysis of the four COs designed in this work has been performed.
During the fabrication of a double gate TFET structure, there is a high chance of gate misalignment which may affect the sensitivity of the sensors. In this paper, we investigated various effects of gate misalignment and switching characteristics of charge plasma-based triple metal double gate vertical TFET on electrical characteristics. We observed effects on analog/RF parameters on the proposed structure such as transconductance (g m), output conductance (g ds), intrinsic gain (A VO), total gate capacitance (C GG), and cut-off frequency (f T), along with threshold voltage (V TH) and sub-threshold slope (SS). The work focuses on the investigation of these parameters in three scenarios of gate misalignment: towards the drain, towards the source, and towards the drain and source with different probable percentages of misalignment. The results are analyzed by considering SiO 2 and HfO 2 as gate oxide materials.
This study presents a comparative analysis of radar cross section (RCS) simulations using Ansys High-Frequency Simulation Software (HFSS) and MATLAB. The primary objective is to evaluate the accuracy and consistency of RCS calculations performed by these two software tools for metallic cylinders. Metallic cylinders are selected as radar targets due to their well-defined and standardized shapes, which enable easier modeling and comparative analysis. To validate the RCS simulations, actual RCS measurements were conducted on an airport runway. The measurements took place at Kuala Lumpur International Airport (KLIA) using an FOD detection system operating at 93.1 GHz. By comparing the measured RCS data with the simulations results, the agreement and reliability of the simulation techniques were assessed, considering metallic cylinders of six different sizes. The findings indicate that the RCS values obtained from measurements align with the simulation results, exhibiting a similar RCS pattern. Both simulations exhibit minimal discrepancies, ranging between 0.01 to 0.1 dBsm. Through the analysis of the simulation results and measurements, valuable insight were gained regarding the performance and effectiveness of HFSS and MATLAB in predicting RCS values. Consequently, this study contributes to the understanding and validation of RCS simulation techniques and their practical applicability in real-world scenarios.
This paper, presents a 4×4 BM based on four direction switch BM antenna array. The proposed design operated at 3.5 GHz. The use of multi-beam antennas or switched-beam antenna arrays (SAAs) promised users of high-gain and large coverage areas for 5G technologies. The BM was implemented by combining 3-dB BLC, two crossovers, and 45 o phase shifters fabricated on the RT5880LZ substrate, with using a triangular slot and T-shape based on the BM design. The proposed design focused on the miniaturization and enhancement of the bandwidth. The return loss and isolation were better than -15 dB at all the ports, according to the simulated and measured result showed that with excellent insertion loss -6.1 ± 2 dB. A fractional bandwidth of 49.7% and the overall dimension were reduced to 56% as compared to the conventional BLC and crossover. Hence, the proposed design of BM performed an excellent size reduction of 80% and improvement bandwidth up to 836 MHz compared to the traditional BM. The switched beam directions were measured at -34 o, -40 o, +32 o and +35 o at 3.5 GHz for each input port of 1-4 excitation. The proposed design BM is suitable of 5G application.