Al-Rafidain Engineering Journal (AREJ)

This paper presented a new structure for the CMOS power amplifiers as a more effective trend to amplify radio frequency (RF) signals compared to polar power amplifiers PA's by using envelope removal and restoration (EER) technique. Polar PA offers high-efficiency RF-modulated linear signal amplification. However, these amplifiers need high uniformity between the amplitude and phase of the modulated signals. The last translates promptly into higher energy consumption. Rather than deconstructing the quadrature signals into the combination of phase and amplitude signals, it is suggested that the CMOS quadrature power amplifier (QPA's) technique had been used to amplify RF signals immediately. The linearity, bandwidth, efficiency, and power consumption of the QPA's has been improved by separate amplitude and phase quadrature signals. The quadratic geometry architecture contains two bridges from modulated PA's that are able to treat negative or positive voltages, modulation, and RF-power bundling. The design of the new structure is compared with respect to parameters such as fundamental frequency, power gain, PAE, output power, technology or fabrication process, and number of stage transistors. Simulation results for PA's design using CMOS process show an effective quadrature model by a power-added-efficiency (PAE) of 78.413% at a maximum output power of 21.619dBm. The third intermodulation IDM3 is -49.2dBc at output power driven at frequency 2.4 GHz and input power greater than 20dBm. The amplitude and phase distortion has been obtained of 1.4 and 0.26 ᵒ/dB respectively at 50MHz of bandwidth for modulated signals.

                     Filters are two-port networks that may pass or attenuate frequencies within defined ranges and can alter the frequency response of any system. In the present research study, the goals and optimization controller embedded with (ADS2019) are used to design Butterworth and Elliptic bandpass filters with frequency ranges of (18GHz – 38GHz), a bandwidth of (7GHz), stopband attenuation of (S21=-60dB), and passband attenuation of (S21=-1dB). Three types of each filter (Hp-Lp 6th order – 3rd order – 6th order) are simulated and optimized to choose the best (C, L) values. The selected filters are redesigned using the Design Filter Guide, and the simulation during this phase yields different values for (C, L). The designed circuit is then transformed into a microstrip model using transmission lines for open and short circuits. The study investigates the differences between each filter in BW-f center- attenuation at the stopband.In the last phase of the study, the circuit of each filter is transformed using a microstrip transmission line to obtain the (W, L) for each component of each filter. Finally, the study compares past studies and research projects in this field.

This paper presents a method to control on single real-frequency transmission zeros (TZs) position in the reject band for third-order waveguide band pass filter (BPF). The external couplings are achieved by using a coaxial probes while the internal couplings are achieved by using short-circuit metallic posts. The TZs appear are generated by forming a triplet, i.e., multipath cancellation between non-adjacent resonators. The dimensions of the metal post between non-adjacent resonators are adjusted to control the position of TZs in the rejection band. A third order waveguide generalized Chebyshev BPF is simulated with HFSS at a center frequency of 28 GHz to validate the design method. The simulated insertion loss is 0.05 dB and the bandwidth (BW) is 500MHz. The simulation demonstrates the compatibility of the presented filtering structure with 5G applications.

Millimeter-wave (mmwave)is an attractive option for high data rate applications in the 5G wireless communication that requires proper beamforming, channel tracking, and channel change. Adaptive beams are formed by relying on adaptive algorithms. In this paper, we study, analyze, and compare the performance of the least mean square algorithm (LMS) and normalized least mean square (NLMS) for tracking channel status and transmit array beam. When using LMS algorithms and natural NLMS algorithms, an adaptive filter usually results in a trade-off between convergence velocity and adaptive accuracy. The results showed that the LMS algorithm is one of the simplest types of algorithm but it needs a large step size to obtain faster system convergence and stability. NLMS algorithm is a special application for the LMS algorithm, in which NLMS algorithm takes into account the change in the signal level when applying the filter and specifies the normal step size parameter μ. this leads to stability as well as rapid convergent adaptation of the algorithm. 

Massive MIMO system in the fifth generation can consume a large amount of energy. In this research, the selection of antennas was studied based on several algorithms and a new algorithm was proposed for the selection of antennas. The results showed through a comparison between the approved and proposed methods in the research in terms of capacitance that The proposed algorithm is the closest in terms of capacity to the ideal case, as this method is considered almost ideal for its application in multi-input and multi-output systems to improve performance in the fifth generation, followed by the greedy algorithm and algorithm norm, as it was noted from During the comparison in terms of energy efficiency, it is possible to increase energy efficiency when choosing a certain number of antennas