F.M. Ghannouchi

University of Calgary · Department of Electrical and Computer Engineering

Based on the linear responses and nonlinear (NL) loss effects of ferrite, a filtering–limiting (FT) integrated device applicable to the high-power microwave (HPM) electromagnetic environment is proposed. The small-signal bandpass filtering characteristics of the FT device with polycrystalline yttrium iron garnet (YIG) as a substrate are achieved us...

In this letter, a novel high-power microwave (HPM) phase shifter (PS) is proposed. The PS is based on the principle of tunable electrical length and can shift phase by turning a rotary choke piston in a toroidal-shaped phase-shifting segment. The simulation results show that the PS can shift phase linearly over 360 $^{\circ}$ in the frequency rang...

This article presents an ultra-broadband distributed efficient power amplifier (DEPA) with reactance compensation and adaptive biasing. It is illustrated that the bandwidth of the DEPA can be improved apparently by applying a shunt short-circuited stub at the combining point. The principle of such method is that the back-off impedance variation wit...

The power-limiting performances caused by two types of spin waves in the ferrite microstrip limiter are conducted theoretically and experimentally when narrow microwave pulses are applied for excitation. The theory indicates that the spin waves responsible for nonlinear (NL) power loss are primarily characterized by the applied bias magnetic fields...

An investigation on the phase locking of S-band relativistic magnetrons with an all-cavity-extraction (ACE-RM) structure is carried out. In order not to disrupt the periodic distribution of electric fields in the resonant cavities, an azimuth-uniform coupling structure is introduced, which could achieve a transmission efficiency of over 98% at the...

In this article, the theory and design of high-efficiency broadband continuous class-B/J power amplifiers (PAs) with active second harmonic injection technique have been presented. By injecting the second harmonic component generated by the auxiliary PA, the optimal phase shift parameter $\alpha $ between the drain voltage and current can be sele...

An efficient coaxial superradiant relativistic backward wave oscillator (SR-RBWO) operating at a low magnetic field is proposed and studied. In such SR-RBWO, a coaxial slow wave structure (SWS) is used in the interaction region, the coaxial structure can realize the stable transmission of the intense relativistic electron beam (IREB) in a long inte...

An $\textit{X}$ -band superradiant relativistic backward-wave oscillator (RBWO) operating at a low magnetic field with power conversion efficiency exceeding unity is proposed. The device efficiency is improved from two aspects: beam transmission stability focused by a low guiding magnetic field and microwave transmission efficiency. First, a grad...

In this letter, a highly-efficient Doherty power amplifier (DPA) architecture with generalized parallel-circuit class-EF mode is proposed. With this topology, the ideal harmonic impedance conditions at the deep power back-off (PBO) region and saturation region can remain the same. Based on it, by adding a single harmonic control network (HCN) and a...

High frequency (HF) transmitter implemented with the multioctave broadband power amplifier (PA) is always faced with the problem of interfering harmonics because of the nonlinearity of the PA. With the harmonic‐cancelation digital predistortion (HC‐DPD) scheme, the harmonics at lower frequencies can be canceled by the injected components and the ha...

H-guide and nonradiative dielectric (NRD) waveguide have more favorable prospects in the millimeter wave and even terahertz bands comparing to other waveguides, such as surface plasmon polaritons transmission lines and Goubau line. Basically, the H-guide described in this letter can avoid many of the disadvantages of the other more-conventional gui...

Simulations and experiments of an $\textit{S}$ -band TEM-output relativistic magnetron (RM) driven by split cathode (SC) are proposed. In the previous researches on SC, as a result of the space-charge-screening effect of squeeze-state electrons accumulated nearby the emission surface, the diode current is limited, which finally results in low out...

The purpose of this article is to solve the issue that current high-power microwave (HPM) transmission links are used in the rigid metal waveguide, which causes significant installation difficulties to the system integration. In this article, we design the TM $_{01}$ and TE $_{01}$ high-power handling corrugated flexible waveguides using a numeri...

This article presents a modified transmit/receive (T/R) front-end module (FEM) architecture with improved transmitter (TX) efficiency. Single-pole double-throw (SPDT) switch is commonly adopted in conventional FEM for T/R isolation, but its insertion loss (IL) deteriorates TX efficiency greatly. To alleviate this problem, a post-matching (PM) archi...

This article presents accurate, efficient and reliable small-signal model parameter extraction approaches applied to Gallium Nitride (GaN) High Electron Mobility Transistor (HEMT). Firstly, a scanning-based systematic model parameter extraction methodology is developed. Then, newly reported Optimization Algorithms (OAs) namely Marine Predators Algo...

Power domain nonorthogonal multiple access (PD-NOMA) is an effective technique to improve spectral efficiency. When the power allocation strategy changes, the power of the signals synthesized by multiple users will change accordingly. This leads to a change in the nonlinear characteristics of the power amplifier (PA) and a deterioration of the bit...

With the advent of the fifth generation (5G) New Radio (NR), the Non-Terrestrial Network (NTN) stands out as a solution to enable wider coverage of broadcast satellites. NTN systems require higher data rates and bandwidth. Digital predistortion (DPD) is commonly adopted as an effective method to enhance the power efficiency of broadcast satellites’...

The parallel-pumped spin-wave instability (SWI) threshold power, $P_{\mathrm{th}}$ , of polycrystalline yttrium iron garnet (YIG) excited by microwave pulses with the varied rising-edge time was investigated theoretically and experimentally. The SWI threshold model associated with the rising-edge time $t_{r}$ is developed in terms of the attrib...

A compact relativistic magnetron with diffraction output (MDO) of TEM mode has been investigated experimentally by using the EPA-90 high-voltage electron accelerator. The purpose is to verify the diffraction output in low-order mode predicted by numerical simulations. The diagnostic results have indicated that the MDO with all cavity extraction rea...

In this article, a uniform neural network (NN) digital predistortion (DPD) model of radio frequency (RF) power amplifiers (PAs) is proposed for dynamic applications, which is suitable for RF PAs under various operating conditions without updating the coefficients. With the development of communication systems, it is difficult for the DPD to track t...

In this paper, a novel X-band TM 01 –TE 01 mode converter for high-power microwave (HPM) system is proposed. To realize the compact design, a helical corrugated waveguide with large deformation is employed to convert the TM 01 mode into TE 01 mode. By optimizing the structure parameters, the simulation results demonstrate that the maximum conversio...

High frequency (HF) transmitters implemented with the multi‐octave power amplifier (PA) are always faced with the problem of interfering harmonics because of the nonlinearity of the PA. In this paper, the harmonic cancelation digital predistortion (HC‐DPD) scheme is proposed and well discussed to cancel the in‐band intermodulation distortion (IMD)...

Generalized memory polynomial (GMP) model is widely used to build and compensate for the nonlinearity of power amplifier (PA). To reduce the complexity of the GMP model, a pruning method represented by the doubly orthogonal matching pursuit (OMP) algorithm was proposed. Lookup table (LUT) based predistortion blocks for compensating PAs are widely u...

This article proposes a broadband high-efficiency parallel-circuit (PC) class-EF power amplifier (PA) along with a quarter-wavelength stub for the first time. By adding a reactive element ${X}$ , the design space is expanded so that the impedance terminations of the fundamental and harmonics are no longer fixed points. Based on the broadband capa...

This article presents two novel digital predistortion (DPD) based architectures that jointly mitigate the inphase/quadrature (IQ) modulator impairments and the power amplifier (PA) nonlinear distortion in wireless transmitters. The proposed architectures are multibit cartesian and complex delta-sigma modulator-based joint DPDs, called CDSM-JDPD and...

This article extends the theory of Class-X power amplifiers (PAs) with maximally flat waveforms by considering an arbitrary number of harmonics in the analysis. The proposed theory shows that the maximally flat voltage and current waveforms can be established with a proper fundamental load corresponding to a set of randomly and independently distri...

In this paper, we proposed a novel radio over fiber (RoF) transmitter architecture to achieve high dynamic range (DR) suitable for millimeter wave (mm-wave) applications, supported by simulation and experimental validations. The designed test benches achieved more than-41 dBc adjacent carrier leakage ratio (ACLR) for a fifth generation/new radio (5...

This article extends the theory of Class-X power amplifiers (PAs) with maximally flat waveforms by considering an arbitrary number of harmonics in the analysis. The proposed theory shows that the maximally flat voltage and current waveforms can be established with a proper fundamental load corresponding to a set of randomly and independently distri...

In this paper, a low complexity moving average nested generalized memory polynomial model (MAN-GMP) is proposed for digital predistortion (DPD) of broadband power amplifiers (PAs). As the signal bandwidth increases drastically, the strong nonlinear distortions, especially those induced by the memory effect, are generated from the highly efficient P...

A preliminary investigation on S-band multi-port relativistic magnetron (RM) is carried out, which is targeted at the application of high-power microwave (HPM) phased array system. For such system, the phase synchronization and stabilization of sources are crucial. In proposed multi-port RM, the HPMs in four independent output ports are extracted f...

In modern wireless compact transmitters, Power Amplifier (PA) behavior is considerably affected by the impedance mismatch between the PA’s output and the antenna’s input. This PA’s output mismatch results in a reflection at the PA–antenna interface. In this brief, reflection-aware PA modeling and digital predistortion (DPD) techniques are proposed...

High frequency (HF) transmitter implemented with the multioctave broadband power amplifier (PA) is always faced with the problem of harmonics because of the nonlinearity of the PA. With the previous harmonic cancellation digital predistortion (HC-DPD) scheme, harmonics and the fundamental components, as a whole, are modeled with a uniform memory po...

The dynamic radio resource management technology is an essential technology in high throughput satellite (HTS) communications. Aiming at the problem that the traditional static radio resource allocation is difficult to meet the dynamic traffic, the dynamic radio resource allocation based on the meta-heuristic algorithm has been extensively studied....

In this article, we propose a new robust and highly efficient digital predistortion (DPD) concept for the linearization of wideband RF power amplifiers (PAs). The proposed approach is based on the combination of a parallelized delta-sigma modulator (DSM) and a forward model of the PA. This concept applies multi-rate techniques on a DSM that incorpo...

In this brief, a novel impedance matching network (IMN) for designing high-efficiency power amplifiers (PAs) is presented. With this method, the fundamental matching network (FMN) and the harmonic control network (HCN) are incorporated into a single network, which is composed of a $\boldsymbol{\lambda }$ /8 ( $\boldsymbol{\lambda }$ is wavelengt...

A number of machine learning (ML) algorithm based small signal modeling of Gallium Nitride (GaN) High Electron Mobility Transistors (HEMTs) have been reported in literature. However, these techniques rarely provide any inkling about their suitability in modeling GaN HEMTs under varied operating conditions. In this context, this paper thoroughly inv...

The peak-to-average power ratio (PAPR) reduction and linearization techniques are both effective methods to improve the efficiency of the transmitter in digital video broadcasting (DVB) systems. Traditional methods deploy the PAPR reduction model and the linearization model, respectively, without considering their mutual influence. Therefore, the j...

This article presents a highly linear Doherty power amplifier (DPA) based on phase mismatch. When output phase mismatch (OPM) is introduced, i.e., the phase shift of the output impedance transformer deviates from 90°, the power-combining network (PCN) will exhibit a certain amplitude-to-phase (AM-PM) characteristic. When input phase mismatch (IPM)...

This paper investigates the effects of the signal average power and the ambient temperature on the behavioral modeling and pre-distortion of high-power amplifiers concurrently. The measurement results showed that in addition to the signal average power, the behavior of a high-power PA is a function of ambient temperature as well. This paper propose...

This letter presents a high precision wideband active vector-modulating phase shifter with high dynamic range gain control ability. Compared with conventional switching-filter phase shifter and vector-modulation phase shifter, this $\Delta $ – $\Sigma $ modulated vector phase shifter can provide quasi-continuous phase and gain control capability...

In this article, a fully integrated dual-band gallium nitride (GaN) Doherty power amplifier (DPA) based on multi-resonant circuits (MRCs) is presented. A lumped T-type network in combination with the output capacitances of the main and auxiliary transistors is able to realize the quarter-wavelength transformer (QWT) in DPA, and its component values...

The convolutional neural network (CNN) based power amplifier (PA) model has been proven to reduce the model complexity significantly. However, due to the calculation mode of the convolutional structure, the application of the CNN-based predistortion model still faces the problem of high computational complexity. In this letter, we use one lightweig...

This brief presents a new reconfigurable complex multi-band delta sigma polar modulator (CMB-DSPM) architecture for multi-band transmission. In this brief, a $6^{\mathrm{ th}}$ order band-pass delta sigma modulator (DSM) is designed and implemented for reconfigurable triple-band transmission. The proposed DSM architecture utilizes the advantage o...

Localization techniques are becoming key to add location context to Internet of Things (IoT) data without human perception and intervention. Meanwhile, the newly-emerged Low-Power Wide-Area Network (LPWAN) and 5G technologies have become strong candidates for mass-market localization applications. However, various error sources have limited localiz...

Abstract A design scheme is presented for an all‐pass coupled‐line (APCL)‐based dual‐band impedance‐matching network. Salient features include a highly flexible frequency ratio (r) (high of 15 and low of 1.2) and impedance transformation ratio (k) (high of 9 and low of 0.2) simultaneously at two arbitrary, uncorrelated frequencies of interest. The...

Digital predistortion algorithms are demonstrated for 5G back-bone optical systems employing 64-QAM and 256-QAM advance modulation formats. The performance of the digitally linearized systems is compared experimentally and using simulation with standard coherent transmission systems.

Conventional digital predistortion (DPD) techniques are facing the challenge of complexity in the fifth generation (5G) and beyond concurrent dual-band terminal transmitters. This article proposes novel low-complexity behavior models for the DPD of terminal power amplifiers (PAs). Derived from the conventional memory polynomial (MP) model, the new...

Neural network (NN)-based models are perceived as being accurate models for power amplifier (PA) behavioral modeling and digital predistortion (DPD) applications. However, the complexity of NN's models in terms of the number of coefficients increases with the memory depth, nonlinearity order, signal bandwidth, and the number of carriers. In this ar...

The behavior model based on the artificial neural network has been widely used in the broadband power amplifier (PA). Although the deep neural network (DNN) performs well in the PA modeling with high-dimensional inputs, the training time of the DNN model is still long. This letter proposes a PA modeling method based on transfer learning to reduce t...

This article presents a generalized theory and new design methodology for reverse-load-modulated dual-branch (RMDB) power amplifiers (PAs), which uses a current-biased transistor in the main branch to realize optimal load modulation without using the impedance transformers at the output of the PAs. Consequently, this topology offers a proper load m...

In this paper, a novel multi-stream spatial digital predistortion (DPD) technique is proposed to model and linearize the fully-connected (FC) hybrid beamforming (HBF) transmitters. The proposed scheme solves the DPD implementation issue in the FC HBF array by estimating and linearizing the beam signals instead of the individual PAs. In FC HBF syste...

In this article, a novel broadband millimeter-wave (mm-wave) front end (FE) based on the asymmetric switch network structure is proposed for multistandard fifth-generation (5G) applications. The asymmetric switch network consists of a bidirectional impedance transformation network and a T-type topology single-pole single-throw (SPST) switch. In the...

A high output power and high-efficiency L-band inverted relativistic magnetron (IRM) driven by a virtual cathode (VC) is proposed. By switching the configuration of cathode and anode, a greater magnitude of current could be generated from an external annular emission surface. In order to excite the desired mode more efficiently and enhance the mode...

This article presents a fully integrated distributed efficient power amplifier (DEPA) for fifth-generation (5G) massive multiple-input multiple-output (MIMO) applications. In conventional DEPA, an individual input matching network (IMN), power splitter, and phase compensation line are used for each auxiliary power amplifier (PA) unit, resulting in...

In this article, a continuous-mode inverse class GF (CCGF <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> ) power amplifier is introduced based on a new closed-form expression for the drain current. This analytical expression is utilized to exploit second source harmonic impedance manipulation...

An L-band all cavity axial extraction (ACAE) relativistic magnetron (RM) with a split cathode is proposed. The proposed RM is driven by virtual cathode that formed by axial flow of electrons from two conical emitters at both sides of slow wave structure, which is different from other RM that powered by radial flow of electrons from a cathode inside...

This paper proposes a novel approach and apparatus along with its calibration method to use the digital predistortion (DPD) technique in radio-over fiber (RoF) cloud RAN (C-RAN) transmitters that encompass physically spaced central baseband unit (C-BBU) and remote radio head (RRH). The proposed approach requires a calibrated observation path (COP)...

A compact relativistic magnetron (RM) system with diffraction output is proposed, whose novelty lies in the omnidirectional radiation through the slotted waveguide array antenna. In the array antenna, a periodically slotted ridged circular waveguide is employed to obtain omnidirectional radiation and decrease its radius. Meanwhile, the RF field is...

Power amplifier (PA) models, such as the neural network (NN) models and the multilayer NN models, have problems with high complexity. In this article, we first propose a novel behavior model for wideband PAs, using a real-valued time-delay convolutional NN (RVTDCNN). The input data of the model is sorted and arranged as a graph composed of the in-p...

An improved hybrid parameter‐extraction technique is proposed for the small‐signal modeling application in AlGaN/GaN high electron mobility transistors (HEMTs). The capacitance partitioning characteristics of cold pinch‐off GaN device with non‐field‐plate and field‐plate structures are reinvestigated and the scanning range of parasitic capacitances...

In this brief, a 24–29.5 GHz millimeter-wave (mm-wave) voltage-combined Doherty power amplifier (DPA) based on compact low-loss combiner is proposed for the fifth-generation (5G) applications. By maximizing the use of parasitic parameters in the circuit, a compact low-loss combiner is proposed to achieve the required impedance transformation with o...

This paper presents an extensive study and demonstration of efficient electrothermal large-signal GaN HEMT modeling approaches based on combined techniques of Genetic Algorithm (GA) with Artificial Neural Networks (ANN), and Particle Swarm optimization (PSO) with Support Vector Regression (SVR). Another promising Gaussian Process Regression (GPR) b...

This paper proposes a full-duplex Radio-over-Fiber-over-Space (RoFoS) transceiver’s architecture with mixerless frequency conversions. The polarization splitting of the optical carrier into two orthogonal polarizations provides away to carry both downlink (DL) and uplink (UL) optical signals in one optical channel. In this work, the UL and DL signa...

This paper presents a new design methodology for broadband Doherty architecture using the three-port input and output networks technique. The proposed topology was developed to overcome the Doherty power amplifier (DPA) bandwidth limitations. The output three-port network performs the impedance matching from any load impedance to the optimum loads...

In this paper, a new method‐of‐moments‐based approach is proposed for the analysis of non‐uniform lossy substrate integrated waveguides (SIW) transmission lines. The approach incorporates Chebyshev expansion in the frequency domain to compute the scattering parameter matrix of the line. To validate the proposed approach of non‐uniform structures ar...

The power amplifier (PA) behavior models based on deep neural networks (DNNs) have been widely used. However, it is challenging to balance the network depth, the number of neurons, and the combination of input terms. Accordingly, how to obtain a suitable DNN model becomes a problem. This letter proposes a method to acquire the corresponding optimal...

This paper demonstrates the analysis of a long-distance high-power microwave wireless power transmission (MWPT) system based on asymmetrical resonant magnetron and cyclotron-wave rectifier. In the system, the novel magnetron with the asymmetrical resonant cavity, the straps, and the output loop coupling circuit can effectively promote the beam–wave...

High frequency (HF) transmitter whose operating frequency range is about four octaves is always faced with the problems of harmonics because of the nonlinearity of the power amplifier (PA). The conventional analog harmonic cancellation scheme uses lossy and bulky filter banks. The digital harmonic cancellation scheme requires a high sampling rate....

The paper demonstrates, for the first time, a high power (200W) load modulated balanced amplifier (LMBA) targeting 5G cellular infrastructure applications. Both amplitude and phase of the injected signal applied to the control power amplifier (CPA) are configured using a dynamic phase shaping function along with a pre-distortion digital front-end....

Centralized radio resource management method puts all of the computational burdens in an agent, which is unbearable with the increasing of data dimensionality. This paper focuses on how to schedule limited satellite-based radio resources efficiently to enhance transmission efficiency and extend broadband coverage with low complexity. We propose a c...

The impact of input nonlinearity due to the nonlinear C GS - GS profile on load harmonic tuned power amplifier (PA) performance is qualitatively discussed. It is experimentally validated by pulsed vector load pull measurements that both Class B and Class F PA operation are quite sensitive to the source second harmonic (Z 2S ) termination with an ef...

This article proposes a power scalable beam-oriented digital predistortion (PSBO-DPD) architecture suitable for linearizing PAs in compact hybrid massive multiple-input multiple-output (MIMO) transmitters, without the need to implement a dedicated observation path for each PA. Based on an assumption that all PAs are similar, the feedback configurat...

We propose a compact dual-frequency relativistic magnetron with TEM mode output. The resonant system consists of two axially separated beam-wave interaction regions for generating dual-frequency microwave. Under the same diode voltage and axial magnetic field, the RF field of the operating π -mode can almost be simultaneously established. Furthermo...

A comprehensive time-domain modeling and a generalized design methodology for input and output waveform engineered Class-F power amplifiers (PAs) are presented in this paper. A closed-form relationship between input nonlinearity and second harmonic source impedance (Z2S) termination is presented from which efficiency and output power performance ar...

This letter proposes a novel methodology and a metric for the assessment of the linearizability of broadband nonlinear power amplifiers (PAs). Validation of the proposed methodology and the proposed metric on two linearized Doherty PAs (DPAs) using digital predistortion (DPD) technique was carried out and it demonstrated the suitability and appropr...

High peak-to-average power ratio (PAPR) in orthogonal frequency division multiplexing (OFDM) systems is one of the major drawbacks in wireless transmitters. In this letter, a novel low complexity PAPR reduction method based on the real-valued neural network (NN) is proposed. This method first builds the PAPR reduction module using the real-valued N...