Showing papers by "Mohammed Abo-Zahhad published in 2018"

High-Efficiency CMOS RF-to-DC Rectifier Based on Dynamic Threshold Reduction Technique for Wireless Charging Applications

Abstract: This paper presents a high-efficiency CMOS rectifier based on an improved dynamic threshold reduction technique (DTR) The proposed DTR consists of a clamper circuit that biases the gates of pMOS diode switches through a capacitor and diode-connected pMOS transistor The clamper is used to insert a negative dc level to the input RF signal; therefore, more negative RF signal can be obtained to bias the gates of the main rectifying pMOS devices during its conduction phase This mechanism reduces the threshold voltage of the main pMOS transistors and increases their sensitivity to the RF input signal The proposed rectifier is implemented in a 018- $\mu \text{m}$ CMOS technology and tested The measurement shows a peak power conversion efficiency of 86% and an output voltage of 052 V at an input power of −165 dBm and an input frequency of 402 MHz The core area of chip excluding measurement pads is 0024 mm2

Dual Band VCO Based on a High-Quality Factor Switched Interdigital Resonator for the Ku Band Using 180-nm CMOS Technology

Abstract: A dual band and low phase noise Ku-band voltage-controlled oscillator (VCO) using 180-nm CMOS technology is presented in this brief. The proposed VCO employs a switched notch filter that can operate in the low and high band, which depends on the state of nmos transistor and has a quality factor that is higher than that of a conventional inductor–capacitor (LC) resonator. The proposed resonator doubles the quality factor compared to LC in the technology and reduces the total die area. The first band is realized by the switched interdigital resonator when a nMOS transistor is in the off state. Furthermore, the second band is realized by turning nmos transistor to the on state, which is located between two fingers in the proposed resonator. The chip is implemented in 180-nm CMOS technology, and found that the proposed VCO operates from 15.5 to 16.7 Hz (low band) and 16.6 to 17.4 GHz (high band). At 1.8-V power supply, the power consumption of the oscillator core is 5.4 and 7.2 mW in the low- and high-frequency bands, respectively. The measured phase noise is −107 dBc/Hz at 1 MHz offset from 16.7-GHz carrier frequency.

Dual-band Rectenna Using Voltage Doubler Rectifier and Four-Section Matching Network

Abstract: A dual-frequency rectenna is introduced in this paper. An enhanced-gain antenna is integrated with the rectifying circuit for increasing the rectenna capability for scavenging. A voltage doubler circuit is used for the rectification. Moreover, a four-section matching network is employed for the matching between the antenna and the rectifier. The measured results reveal that the RF-to-DC conversion efficiency is more than 50% over wide range of the input power, from-3.5dBm to 10. 5dBm at f 1 and from -4.5dBm to 11dBm at f 2 , with maximum conversion efficiency of 63% and 69% at input power of 7dBm and 3. 5dBm, respectively with resistive load of$1K\Omega$. Further-more, the measurements illustrate good agreement between the simulated and measured results.

Real-Time Algorithm for Simultaneous Vehicle Detection and Tracking in Aerial View Videos

Abstract: Automatic detection and tracking of multiple vehicles in airborne videos is still a challenging problem due to camera movement, vehicle occlusion and the need for computational resources. This paper presents a robust and efficient real-time method for automatic detection and tracking of vehicles in airborne videos. The detection process is based on a combination of Top-hat and Bot-hat transformation aided by the morphological operation. Background objects are removed through analyzing feature points motion of the obtained object regions using K-means clustering and KLT tracker. The obtained vehicles features are grouped and clustered into separate vehicles based on their motion properties. Finally, a connecting scheme is presented to determine the connectivity of vehicle cluster with the corresponding cluster in the vehicles trajectories. Experiments conducted on videos representing airborne cameras verify the excellent performance compared to other existing approaches.

Energy Efficient Framework for Multiuser Downlink MIMO-NOMA Systems

Abstract: Non-Orthogonal Multiple Access (NOMA) is a promising multiple access technique for the 5th generation (5G) mobile communication systems. In this paper, an energy efficient power allocation scheme is derived for a general number of users per cluster multiple input multiple output (MIMO) downlink NOMA system. The proposed scheme idea is based on converting the difficult energy efficiency power allocation problem into an equivalent spectral efficiency power allocation problem and then dividing this equivalent problem into multiple simple cluster sum rate maximization problems. In addition, a user clustering scheme is proposed to maximize the NOMA system energy efficiency by first designing the detection vectors to convert the MIMO users channel matrices into their equivalent channel vectors and distribute the users on the clusters based on their equivalent channel gains. The users are clustered such that those with the largest equivalent channel gains are selected as cluster heads and the rest of users in each cluster are selected to maximize the equivalent channel gain difference between each other. Numerical results show that the proposed framework improves the system energy efficiency of the MIMO NOMA system at different values of the total transmit power, the minimum required date rates, the number of users per cluster and at different users’ distance distribution scenarios.

Convex lenses horn antenna microwave hyperthermia scheme

Abstract: This paper presents a new preclinical microwave hyperthermia system based on the combination among horn antenna and convex lenses. The horn antenna is designed to resonate at 3 GHz which is reported for hyperthermia therapy. Two convex lenses are designed and incorporated with the designed horn antenna and the reported breast phantom. The proposed system aims to heat up the tumor region above 42 ° C while keeping the surrounding area temperature unchanged as possible to protect them from damage. Specific Absorption Rate (SAR) and breast phantom thermal distribution are studied with and without using lenses at different inclination angles. The proposed system has the advantage of heating up different zones separately while keeping other regions temperature unchanged. Simulation results show that, the breast temperature can be elevated by 10 ° C above the normal body temperature.

Primary User Detection in Cognitive Radio Networks Over Fading Channel Using Compressed Sensing

Abstract: Compressed spectrum sensing has gained considerable importance among researchers in the field of concern as a solution for wideband cognitive radio networks. Recently, published works on detecting primary users' signals presented sustainable results by using small compression ratios over the AWGN channel. To the best of our knowledge, since the performance of compressed measurements based detection has not been investigated yet over fading channels, the current study, therefore, presents the performance of compressed measurements based energy detection over Rayleigh fading channel. The proposed work has been implemented by means of MATLAB software. In comparison with the traditional compressed energy detection over the Rayleigh fading channel, the results show that our proposed technique is better in detection performance.

A Wideband Dielectric Resonator Antenna with Truncated Ground for 5G Applications

Abstract: In this paper, we propose a wideband antenna that consists of two closely separated dielectric resonator antennas (DRAs), and fed by a microstrip antenna, for 5G applications. The dimensions of the two DRAs are designed such that they resonate at two close and contiguous resonance frequencies to enhance the antenna bandwidth. Moreover, a truncation in the ground has been proposed such that the feeding microstrip antenna attains a third resonance frequency that is close to the resonances of the two DRAs. As such, the three resonance frequencies form a wide contiguous bandwidth of 12-24GHz, with fractional bandwidth of 66%, at center frequency of 18GHz. Furthermore, the utilization of the two closely separated DRA elements enhances the gain of the antenna as they act as antenna array elements, whereas there is only one feeding port, which simplifies the antenna structure. The DRAs widths and lengths are 2 by 2mm and 5 by 1mm, respectively, and the height of both of them is 5.7mm. The gain of the antenna ranges from 4 to 8dBi over the operating bandwidth. The antenna is fabricated and good agreement is attained between measured and simulated results.