Narrow Results

This paper presents the design of a new Digital Variable Gain Amplifier cell (DVGA). The proposed circuit based on transconductance, gm, amplifier and a transconductance amplifier is analyzed and designed for a cognitive radio receiver. The variable-gain amplifier (VGA) proposed consists of a digital control block, an auxiliary pair to retain a constant current density, and offers a gain-independent bandwidth (BW). A novel cell structure is designed for high gain, high BW, low power consumption and low Noise Figure (NF). The Heuristic Method is used to optimize the proposed circuit performance for high gain, low noise and low power consumption. This circuit is implemented and simulated using device-level description of TSMC 0.18$\mu$m CMOS process. Simulation results show that the DVGA can provide a gain variation range of 54dB (from 54dB to 0dB) with a 3dB BW over more than 110MHz. The circuit consumes the maximum power of 0.65mW from a 1.8V supply.

A miniaturized high-gain (MHG) ultra-wideband (UWB) unidirectional monopole antenna with defected ground structure (DGS) is designed for ultra-wideband applications. The MHG antenna is printed on the FR4 substrate material with an overall size of 26.6-mm $\times$ 29.3-mm $\times$ 1.6-mm, which operates over the UWB frequency range and achieves the bandwidth between 3.1GHz and 10.6GHz. This high-gain unidirectional antenna exhibits a peak gain of 7.20dB with an efficiency of 95%. The compact antenna is a simple overlay design of circular and rectangular patches with the partial ground plane exhibiting high gain and better directivity. The overlay patch antenna acts as the radiator for wider bandwidth compared to the fundamental design of patch antenna and is matched to an SMA connector via 50$\mathrm{\Omega }$ microstrip feed line. These simulated results are presented using HFSS software package. The designed antennas are fabricated and validated by using Agilent Vector Analyzer.

In this work, a broadband high gain frequency selective surface (FSS)-based microstrip patch antenna is proposed. The dimensions of the microstrip antenna and proposed FSS are $22\mathrm{\text{mm}}\times 22\mathrm{\text{mm}}\times 1.6\mathrm{\text{mm}}$ and $60.8\mathrm{\text{mm}}\times 48.6\mathrm{\text{mm}}\times 1.6\mathrm{\text{mm}}$. A broadband high gain reference antenna has been selected to improve antenna performance. The reference antenna offers 1.2GHz bandwidth with 6.03dBi peak gain. Some modifications have been done on the patch and ground plane to enhance the bandwidth and gain. The impedance bandwidth of 7.70GHz (3.42–11.12GHz) with 4.9 dBi peak gain is achieved by the microstrip antenna without FSS. The antenna performance is improved by using FSS beneath the antenna structure. The maximum impedance bandwidth of 7.70GHz (3.32–11.02GHz) and peak gain of 8.6dBi are achieved by the proposed antenna with FSS. Maximum co- and cross-polarization differences are 21dB. The simulation and measurement have been done using Ansoft Designer software and vector network analyzer. The measured results are in good parity with the simulated one.

In this paper, a novel dual-band monopole planar antenna is presented. The antenna is operated in 28/38GHz and has a bandwidth of 0.5/0.7GHz to operate in 5G frequency bands. Additionally, it exhibits a stable omni-directional radiation pattern with high gain characteristics, which helps to improve the performance of future 5G communication devices. The radiation efficiency achieved more than 94% throughout its operating bands. The numerical analysis has been carried out using a three-dimensional (3D) full-wave electromagnetic solver (ANSYS HFSS). In order to validate the numerical analysis, the proposed antenna has been fabricated and shows a good agreement with simulated results. The antenna has been designed and fabricated on Roger RT/Duroid 5880 dielectric substrate. This paper paves a new idea to design dual-band, simple and miniaturized single-element monopole planar antennas, which would be a good candidate for future millimeter-wave 5G communication systems.

Operational Transconductance Amplifier (OTA) is an important circuit block used in the design of filter, amplifiers and oscillators for various analog-mixed circuit systems. However, design of a low-noise, high-gain OTA with low-power consumption is a challenging task in CMOS technology owing to high-power requirements of OTA for emulating high gain. This paper represents the design of gate-driven quasi-floating bulk recycling folded cascode (GDQFB RFC) OTA which has been shown to provide low-noise operation, emulates high gain and draws very less power. The design utilizes the gate-driven quasi-floating bulk (GDQFB) technique on a recycling folded cascode structure, which enhances the transconductance of OTA and improves its performance. All the post-layout simulation results have been obtained in 0.18-μm CMOS N-well technology using BSIM3V3 device models. The obtained results indicate very high gain of 100.4 dB, gain-bandwidth of 69 kHz, phase margin of 51.9^∘ with power consumption of 2.31μW from ±0.9V supply voltage. The input referred noise emulated by proposed OTA is 0.684, 0.21 and 0.0592μV/√Hz @ 1 Hz, 10 Hz and 1 kHz, respectively. The input common mode range and output voltage swing are found to be −0.402 to 0.669 V and −0.493 to 0.610 V, respectively. Corner simulations and Monte Carlo analysis have been performed to verify the robustness of the proposed OTA. The proposed OTA can be used in design of filters and amplifiers for bio-instruments, sensor applications, neural recording applications and human implants etc.

In this paper, a highly efficient tree-shaped fractal antenna with multi-broadband resonance characteristics is proposed. The proposed antenna exhibits broad operating bandwidth, high gain, and high efficiency characteristics due to the suggested modifications in the antenna geometry. The suggested circular patch is modified by introducing slots in the form of a tree-shaped fractal structure, and the partial ground plane is modified by incorporating a narrow rectangular slot. The proposed antenna is designed on an FR4 substrate of $40\times 25.05\times 1.6$mm³. The prototype of the proposed antenna has been fabricated and tested to justify the simulation results. The measurement results are in good agreement with the simulation that validates the multi-broadband design approach of the proposed fractal antenna. As per the measurement results, the proposed antenna operates at four distinct bands with $-$10dB impedance bandwidths of 600MHz (2.2–2.8) GHz, 1070MHz (3.3–4.37) GHz, 2550MHz (4.75–7.3) GHz, and 2200MHz (9.7–11.9) GHz. Furthermore, a high peak gain of 10.23dB and a peak radiation efficiency of 96.65% are recorded for the suggested fractal antenna. The suggested compact bandwidth enhanced multi-band antenna can be useful for several wireless communication systems such as wireless fidelity (Wi-Fi), wireless local area network (WLAN), Bluetooth, long-term evolution (LTE), C, S and X bands.

In this paper, a high gain nonisolated three-port bidirectional DC–DC converter is proposed to interface solar photovoltaic and battery energy storage system to DC bus with a reduced number of components. Four modes of operation based on the power flow and load demand are identified. The operating principle of the proposed converter and its operational waveform for all four modes of operation is described in this paper. The steady-state analysis of the proposed converter is performed to determine the voltage gain of the converter in all four modes of operation. The steady-state analysis is done for both continuous conduction mode and discontinuous conduction mode; and the boundary condition. The reduced number of components to achieve high-voltage gain ensures the lowering of the cost and weight of the converter. The analytical results are validated utilizing the simulation results from PSCAD and hardware results. Also, the results indicate that the ripple in the current and voltage is reduced significantly.

In this work, a novel multiple input multiple output (MIMO) array antenna system with a large bandwidth and high gain has been simulated, analyzed, fabricated, and measured. The proposed antenna is structured in $2\times 4$ patch configuration along with a cross shaped ground plane loaded with four square and one circular shaped defect. The projected antenna occupies a total size of $43.611\times 43.611\times 0.42{\mathrm{\text{mm}}}^3$. Several slots in an elliptic form have been added to the patches to achieve the required results in terms of wide bandwidth and high gain. The MIMO antenna array is fabricated and experimentally tested to confirm the simulation results. The suggested MIMO array antenna offers an impedance bandwidth of 22GHz covering 22–44GHz wide range of frequencies with a high peak gain of 17dBi at 38GHz. The designed MIMO antenna offers superior diversity performance and it supports several 5G NR bands n257/n258/n259/n260/n261 in the mm-wave spectrum. The suggested MIMO antenna supports 5G application bands that are deployed in UK, USA, China, Europe, Canada, India, and Europe.

This paper describes a four-port MIMO antenna array design featuring bow-tie-shaped slot-loaded patches with wideband capabilities that cover the frequency range from 24.2GHz to 30.8GHz. The proposed antenna design is printed on an FR4 substrate and occupies an area of 25×24mm². The MIMO antenna consists of four antenna arrays that are symmetrically placed in an upper-lower configuration. The bow-tie-shaped slots loaded radiators are separated horizontally by 3.48mm and vertically by 5.94mm. Each antenna array contains two elements that are separated by a distance of wavelength/4. The suggested MIMO antenna array delivers a high gain of 19.09dB at 27.8GHz and has a bandwidth of 6.6GHz that covers the frequency band of 24.2–30.8GHz. The research demonstrates the quality of the proposed MIMO antenna through various diversity parameters such as mutual coupling, port correlation, diversity gain, and data rate that can be transmitted over a communication medium. The simulation results are validated and found to be consistent with the experimental results. The presented antenna covers the entire bandwidth allocated to different regions, including Europe (24.25–27.5GHz), Sweden (26.5–27.5GHz), USA (27.5–28.35GHz), China (24.25–27.5GHz), Japan (27.5–28.28GHz), and Korea (26.5–29.5GHz). The proposed MIMO antenna design could be an excellent option for 26/28GHz 5G NR n257, n258, and n260 bands under mm-wave wireless communication systems.

DC–DC converters have achieved great popularity in recent decades due to their immense penetration in various applications. With this motivation, the authors have conducted a thorough review of recent advancements in various topologies of DC–DC converters. The need for DC power has raised further for certain applications like grid integration of distributed generation (DG), solar photovoltaic (PV), wind power generation (WPG), fuel cells (FC), etc. The investigation of converter topology is performed to achieve the desired objective of a specific application. Like in a PV system, to obtain the inherent capability of a DC–DC converter for operating at the maximum power point (MPP) and thereby electronically extracting the maximum power from the source. Hence, a detailed review of topological advancements on the low to medium-voltage and medium-to-high-power DC–DC converters has been carried out. Moreover, a thorough investigation has been carried out on profuse closed-loop strategies and compared with each other for obtaining the optimum or maximum output performance and thereby obtaining the utmost source utilization. The modern control techniques though have relatively more calculation time but, they tend to reduce the steady-state error that leads to the stabilization of the converter. Lastly, certain applications of the DC–DC converters have been explained to get an overall idea of the usefulness of such power converters.

A novel DC-DC converter with high voltage gain for sustainable energy is proposed, which provides a new substituted topology for low and medium power applications fields where high-voltage conversion is required. The proposed Sepic-based converter combines a coupled-inductor voltage multiplier circuit, which can achieve higher voltage gain and lower voltage stress of power devices when the duty ratio and input voltage are same as the traditional Sepic converter. Moreover, the input current ripple in the proposed converter is decreased, which results in low voltage and high performance semiconductors devices, and then leads to the high efficiency and stability. In this paper, the proposed DC-DC converter is analysed and deduced in detail. Then, simulations and experimental results are presented to verify the feasibility of the proposed DC-DC converter.

An enhanced recycling folded cascode structure is proposed to enhance the gain of the operational amplifier with an auxiliary amplifier and no additional poles. This enhancement was achieved by introducing negative conductance. Under the supply voltage of 1.2V, the OTA was simulated by Spectre in TSMC 90nm CMOS technology. The results show that, the enhanced amplifier get a DC gain enhancement of 40dB compared with the conventional folded cascode. In addition, the gain-bandwidth also obtains 108.9% improvement, which also leads to a better slew rate performance.