Signal Cancellation Research Articles

In-Band Full-Duplex Communications in ATSC 3.0 Single Frequency Network

Wireless in-band backhaul, a.k.a. in-band distribution links (IDL), is a spectrum-efficient and cost-effective enabling technology to the realization of Advanced Television Systems Committee (ATSC) 3.0 in the single frequency network (SFN) mode, where all the transmitter towers are synchronized to transmit the same broadcast signal in the same frequency band. Inter-tower communications network (ITCN) transforms the broadcast towers into a mesh network, thereby introducing datacasting capability to the traditional broadcast network. Both the ITCN and IDL can be operated in the most spectrum-efficient in-band full-duplex (IBFD) mode. In these situations, the ITCN/IDL receivers at the SFN towers receive the signal of interest (SOI) not only severely corrupted by the self-interference signal from its co-located transmitter, but also the co-channel interference signals from neighbouring transmitters. Moreover, the ITCN/IDL signals may be combined with the broadcast signal in the Layer Division Multiplexing (LDM) format to achieve better overall spectral efficiency. Therefore, the LDM inter-layer interference must also be mitigated. In this paper, the interferences for the ITCN/IDL signal in the SFN environment are analyzed, and a novel iterative successive signal cancellation scheme is proposed to effectively mitigate the interferences in the ITCN/IDL signal detection process in ATSC 3.0 SFNs.

Ferrite-Based Multiport Circulators With RF Co-Designed Bandpass Filtering Capabilities

This article reports on the RF design and practical development of multiport circulators with RF co-designed bandpass filtering functionality. The proposed bandpass filter/circulator (BPFC) concept is based on a hybrid implementation approach, where dual-mode non-reciprocal ferrite-based resonators (FBRs) are cascaded with microwave resonators and mixed-electromagnetic (EM) couplings. In this manner, highly selective bandpass filtering transfer functions are created in the direction of propagation, and high RF signal cancellation is obtained in the reverse direction. A design methodology using coupled-resonator-based synthesis is proposed to facilitate the design of these components using well-known filter design techniques. Various electromagnetically simulated and synthesized examples are presented to demonstrate the operating principles of the BPFC approach alongside its applicability to high-order filtering responses. The BPFC concept is further expanded to the realization of multiport non-reciprocal components. For proof-of-concept demonstration, four multiport prototypes were designed, manufactured, and measured at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S$</tex-math> </inline-formula> -band.

IRS-Enabled Breath Tracking With Colocated Commodity WiFi Transceivers

Intelligent reflecting surfaces (IRSs) are a key enabler of various new applications in 6G smart radio environments. This article aims to enhance self-interference (SI) cancellation for breath tracking with commodity WiFi devices by utilizing an IRS prototype system. SI suppression is a crucial requirement for breath tracking with a single antenna site, as the SI severely limits the radio sensing range by shadowing the received signal with its own transmit signal. To this end, we propose to assist SI cancellation by exploiting an IRS to form a suitable cancellation signal in the analog domain. Building upon a 256-element IRS prototype, we present results of breath tracking with IRS-assisted SI cancellation from a practical testbed. We use inexpensive WiFi hardware to extract the channel state information (CSI) in the 5-GHz band and analyze the phase change between a colocated transmitter and receiver with added local oscillator (LO) synchronization. As a result, we can track the breath of a test subject regardless of position in an indoor environment with a room-level range. The presented case study achieves promising performance in capturing the breath frequency and breathing patterns.

Arbitrarily fast delayed signal cancellation PLL for grid‐integration of renewable energy sources

AbstractIntegrating renewable energy sources into an unbalanced distribution network requires fast and accurate extraction of fundamental frequency positive‐ and negative‐sequence components from the unbalanced three‐phase grid voltage signals. For this purpose, various methods are already available in the literature. Out of them, delayed signal cancellation (DSC) is prevalent. Conventional DSC can separate the sequence components using a quarter‐cycle delay. Fast DSC tools can achieve the same with less than a quarter‐cycle delay. However, neither conventional nor fast DSC can handle DC offset without requiring additional delayed signals. This article addresses this issue by proposing a modified DSC to estimate the sequence components with DC offset rejection and having arbitrarily fast convergence speed, that is, low memory requirement. Two equidistant delayed samples of the measured grid voltages/currents are required to implement the proposed technique and can easily be applied in a phase‐locked loop (PLL). Comparative experimental results demonstrate the suitability of the proposed approach over other DSC methods.

An Improved Delayed Signal Cancelation for Three-Phase Grid Synchronization with DC Offset Immunity

The presence of the DC components in the grid voltage adversely affects the performance of the synchronization unit, causing oscillatory and offset errors in the estimated grid information. Several approaches were proposed to address the DC offset problem by incorporating an additional filtering stage to the synchronous reference frame phase-locked loop (SRF-PLL). Removing the DC offset using the modified delayed signal cancelation (MDSC) operator in the inner loop of the SRF-PLL shows a good DC offset elimination with a fast-dynamic response. However, neither a straightforward selection procedure for the MDSC parameters nor a general estimation technique for the grid information is provided. Hence, a generalization for the MDSC is proposed in this paper based on general mathematical expressions to cancel out the DC offset, while meanwhile estimating the grid parameters precisely and rapidly against any delay factor selection. Finally, comprehensive simulation and experimental results compared with other related PLLs are presented to demonstrate the effectiveness of the proposed work.

Modified park transformation of three-phase signals for harmonic extraction with frequency-adaptive capability

To maintain high power quality in a polluted grid with power electronic devices and non-linear loads, the detection and extraction of harmonic components is inevitable, such as for active power filters, regenerative converters, and uninterruptible power supplies. In this paper, the three-phase current/voltage signal is converted to the dq-frame signal with a modification in the angle used for the Park transformation so that with the aid of pre-filtering techniques such as moving average filter and cascaded delayed signal cancellation method, the selected harmonic can be derived easily. With the implementation of the proposed technique, there is no more need for amplitude and phase correction for the extracted harmonic signal previously elaborated in the literature. The proposed scheme is also equipped with a frequency detection technique to be able to follow the frequency variations in the grid. Moreover, some modifications are applied to the detected frequency to restrict the large transients occur when the grid frequency changes suddenly. The simulation tests and results confirm the effectiveness of the proposed schemes.

A Generalized Harmonic Extraction Algorithm Based on Multi-Window Average Filter Under Synchronous Rotating Frame

Various harmonic extraction algorithms have been proposed to improve the steady-state and dynamic performance for active power filter. However, it is difficult to select a suitable method for a certain load current scenario. This article analyses the general characteristics of the harmonic extraction based on the “frequency shift” characteristic by Park transform, and it can be transformed into a low-pass filter under the synchronous rotating frame (SRF) for design. Starting from the typical average filter, a general FIR filter structure called multi-window average (MWA) is proposed. According to the actual load current components, aiming at the shortest delay, the design process and guideline are given. Combined with SRF, the MWA structure can generalize recursive discrete Fourier transform (RDFT), cascade delayed signal cancellation (CDSC) and their derived algorithms, which proves the equivalence between time-based harmonic extraction methods and frequency-based ones. Moreover, using the MWA structure can effectively reduce the complexity of the CDSC algorithm. The experiment proves that the typical RDFT and CDSC harmonic extraction can be equivalently realized by using the SRF-based structure. Under the presence of 6 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</i> + 1 and 12 <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</i> − 2 harmonics, the proposed harmonic extraction time can reach 1/4 fundamental cycle. While greatly reducing the dynamic response time, the MWA structure reveals inherent unity among various harmonic extraction algorithms for the first time.

Revisiting a Debut at a Career's End: David Mamet's Lakeboat (1970/1980)

Revisiting a Debut at a Career's EndDavid Mamet's Lakeboat (1970/1980) Matthew Sorrento On April 13, 2022, I received notice that ReFocus: The Films of David Mamet, a planned anthology in Edinburgh University Press's film studies series, had been cancelled. Co-editors Michelle E. Moore and Brian Brems decided they could no longer in good conscience go forward with the project after Mamet's April 2022 comments to Fox News. Mamet—who won the 1984 Pulitzer for Glengarry Glen Ross (1983)—had made claims about the previous presidential election being stolen and, even more bizarre, that teachers are "inclined" to be sexual groomers of children.1 While in the middle of writing a chapter on Mamet's less-regarded 1997 film, The Spanish Prisoner, for the collection, I could understand Moore and Brems's decision. This cancellation signals an end of extended scholarly commentary of Mamet as an artist, now that he has recently embraced polemical writings for profit. Mamet's right-wing conversion began with his less coherent 2008 piece for The Village Voice, entitled "Why I Am No Longer a 'Brain-Dead Liberal,'" Here, he writes: I began to question what I actually thought and found that I do not think that people are basically good at heart; indeed, that view of human nature has both prompted and informed my writing for the last 40 years. I think that people, in circumstances of stress, can behave like swine, and that this, indeed, is not only a fit subject, but the only subject, of drama.2 Having celebrated humanity under duress, Mamet now condemns such struggles. And with little interest in humanity, his art—including recent plays like Race (2009) and The Penitent (2017), as well as Phil Spector (2013), an HBO TV film that he wrote and directed and which may be his worst [End Page 225] effort onscreen yet—began to lose its way. In both The Secret Knowledge: On the Dismantling of American Culture (2011) and Recessional: The Death of Free Speech and the Cost of a Free Lunch (2022)—and during the latter's press tour, which included the Fox News appearance—Mamet continued with more loose-formed commentary and plenty of "unqualified declarations" (in the words of Christopher Hitchens).3 These books feature the kind of maxims and wide reference points that are present in Mamet's interviews and in his worthy nonfiction on art, such as On Directing Film (1991) and Three Uses of the Knife: on the Nature and Purpose of Drama (1998). However, Mamet's recent political books recycle factoids that attack 1970s counterculture, diversity, and "elected leaders on the coasts." It is a particularly sad outcome for the once-great writer, as he exploits his capacity for turn of phrase to support a right-wing agenda. Earlier in his career, Mamet listened to the voices around him, both literary and media-borne, to develop an ear for dialogue and a style of drama.4 While he is now concerned with financial hegemony, Mamet was previously in tune with the common worker, especially in his debut play, Lakeboat (1970/1980).5 Showing an enthusiasm for differing perspectives, Lakeboat comprises 28 brief scenes set aboard a Merchant Marine steel freighter on the Great Lakes. The play depicts reflections on work and livelihood, including a fireman whose sense of professionalism relies on keeping watch with inaction, as well as seaman Fred, who remains bitter about his alimony payments.6 Audience surrogate Dale Katzman is a young, optimistic college student working onboard for the summer, as the author did at that age.7 Each of Mamet's boatmen could star in their own realistic proletarian drama. These crew members echo working-class theater of the early twentieth century, which ranged from the progressive work of Clifford Odets to thoughtful entertainments like Elliott Lester's play, Two Seconds (1931). Recent commentators have read Lakeboat in a literary scope, tying Mamet's debut to Eugene O'Neill's sea plays (specifically the expressionist The Hairy Ape [1922]), Melville, and Hemingway's Nick Adams.8 Mamet uses Dale Katzman's arrival to the freighter to invoke sea adventures, both coming-of-age ones...

A conducted emission mitigation method for software-defined radios through vector signal cancellation

Recently, Software-Defined Radio (SDR) has gained great popularity owing to its attractive merits, such as flexible signals configuration in multiple channels. However, commercial SDR equipment also has large spurious emissions in the Transmitting (Tx) channel. This paper presents a cascaded model for the Conducted Emission (CE) properties of a general SDR platform, which captures all the key components with high precision. Based on a deeper understanding of the CE properties, a mitigation method is proposed for suppressing the spurious emissions of an SDR Tx channel. This method is based on an efficient vector signal cancellation scheme, in which multiple SDR channels are adopted to suppress the second- and third-order harmonic signals simultaneously. A hardware prototype with dual SDR channels is built and measured for verification. Experimental results show that the suppression level of the third-order harmonic signal is 24 dB on average in the frequency range of 100 MHz to 3000 MHz. The theoretic limit of the suppression level is related to the magnitude and phase errors, and the suppression level may be further improved by calibrating each SDR channel.

Enhancing the Filtering Capability and the Dynamic Performance of a Third-Order Phase-Locked Loop under Distorted Grid Conditions

This work proposes a structural enhancement and a new technique to design the loop filter (LF) of a third-order phase-locked loop (PLL) to enhance the PLL dynamic performance under abnormal grid conditions. The proposed PLL combines a moving average filter (MAF) and an arbitrarily delayed signal cancelation (ADSC) for structural enhancement to achieve DC-offset rejection and harmonics elimination. The window length of the MAF is selected to be one-sixth of the fundamental grid period to remove non-triple odd harmonics and speed up the PLL dynamic response. The triple harmonics are eliminated, adopting the line-to-line voltage concept, while the ADSC operator rejects the DC offset. The LF design is based on a modified third-order polynomial tuned using stochastic optimization to minimize the settling time of the frequency deviation, offering better dynamic performance over the symmetrical optimum method (SOM) and achieving synchronization within one grid cycle. The PLL mathematical model, small-signal model, and LF design based on the modified polynomial are discussed. Finally, the proposed PLL performance is verified numerically and experimentally with comparisons with other PLLs to demonstrate the effectiveness of the proposed work.

A Frequency-Adaptive Delay Signal Cancelation Based Filter to Reduce Position Estimation Error for Sensorless IPMSM Drives

In a sliding mode observer-based sensorless drive system, the estimated back electromotive force (BEMF) always contains abundant low-order harmonics caused by nonideal factors, e.g., flux spatial harmonics, inverter nonlinearity, and current measurement error, resulting in large estimated position errors. In previous studies, adaptive notch filters are usually adopted to suppress the BEMF harmonics. However, these filters suffer from enormous computation and increase system complexity, especially facing numerous low-order harmonics. In this article, a new frequency-adaptive notch filter employing delay signal cancelation (DSC) is proposed, which can be tailored to eliminate multiple harmonics with a simple structure. First, Lagrange interpolation is applied to realize fractional-order delay in the frequency-adaptive DSC (FADSC). Then, a frequency-dividing record method is designed to shorten the recording array length for the FADSC at low speed. Next, a switching procedure is introduced to change the frequency-dividing factor smoothly at different speeds. Finally, the transformation matrix in the DSC is changed in the FADSC by adding the rotation direction to make it suitable to forward and reverse rotations of an interior permanent magnet synchronous machine (IPMSM). The accuracy of the estimated rotor position can be improved by FADSC, which is verified by experiments on a prototype IPMSM.

An Integrated Solar Panel with a Triboelectric Nanogenerator Array for Synergistic Harvesting of Raindropand Solar Energy.

The triboelectric nanogenerator (TENG) is regarded as an effective strategy for harvesting energy from raindrops, and is a complementary solution with solar cells to achieve all-weather energy harvesting and sustainable energy supply. However, due to the irregularity of natural rainfalls in the volume, frequency, density, and location, designing high-efficiency raindrop TENG (R-TENG) arrays faces great challenges. In this work, a highly transparent, large-area, and high-efficiency R-TENG array with rational material choice, electrode structure, and array distribution is developed for efficiently harvesting irregular raindrop energy. The problem of electrical signal cancellation among adjacent raindrops can be fully avoided, as viewed from the high-resolution space-time analyses of high-speed camera and electrical signal characteristics. With the rationally designed electrode instead of multiple complex electrodes, all charges can be exported by the R-TENG array in a simulated irregular raindrop scenario. Moreover, it is demonstrated that the R-TENG possesses higher average power density (40.80mW m-2 ) than that of the solar cell (37.03mW m-2 ) in rainy condition. Additionally, a self-powered wireless light-intensity-monitoring system is demonstrated for real-time and all-day weather monitoring. This work provides useful guidance for designing high-efficiency TENG arrays integrated with solar panels for harvesting irregular raindrop energy and solar energy.

Satellite-transition double cross-polarization HETCOR under fast MAS

Double-cross polarization to the satellite-transitions (STs) of half-integer quadrupolar nuclei is demonstrated using proton-detected heteronuclear correlation (HETCOR) under fast magic-angle spinning (MAS). By placing the rf frequency away from the central-transition (CT) and selective to the STs, average Hamiltonian theory shows a scaled effective rf field with a phase equal to the complex ST spinning sideband being irradiated. Such an effective rf field can excite and spinlock STs but the phase spread usually leads to signal cancellation in one-step excitation or cross polarization experiments. The cancellation does not occur for two-step double cross-polarization (DCP) HETCOR experiments, therefore high efficiencies can be obtained. With careful magic-angle calibration, ST and double-quantum ST (DQST) HETCOR experiments are demonstrated with the 35Cl nuclei in histidine·HCl·H2O. These experiments provide additional information over the commonly observed CT spectra and near isotropic resolution in the case of DQST of spin S = 3/2 quadrupolar nuclei.

Immunity to Mutual Interference in Coded Phase-Shift LiDAR

When the light detection and ranging (LiDAR) scans a space, the echo signal affected by diffuse reflections may be captured by other LiDAR detectors to interfere with their echoes. The ghost points and missed detections are induced by the co-frequency interference in the phase-shift LiDAR. An interference cancellation with a maximum likelihood estimation (ICMLE) signal processing scheme is presented based on the coded phase-shift LiDAR to avoid mutual interference in this paper. The delay time is estimated with maximum likelihood estimation after each component signal is identified from the mixed signal on account of the correlation between the codewords, followed by cancellation of the component signal from the mixed signal step-by-step. The received signal model with mutual interference is developed, and the Cramer-Rao bound (CRB) is theoretically derived to evaluate the performance of the estimators. The Monte-Carlo analysis shows that the component signals can be recognized from the mixed signal with the ICMLE scheme. The mean square error (MSE) of the delay time for the mutual interference of two-channel signals is close to the CRB. The experimental results demonstrate that the ranging is feasible with a range precision of 8.44 × 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{-3}$</tex-math></inline-formula> m using the echo signal estimated by the proposed solution.

Transcranial Doppler analysis based on computer and artificial intelligence for acute cerebrovascular disease

Cerebrovascular disease refers to damage to brain tissue caused by impaired intracranial blood circulation. It usually presents clinically as an acute nonfatal event and is characterized by high morbidity, disability, and mortality. Transcranial Doppler (TCD) ultrasonography is a non-invasive method for the diagnosis of cerebrovascular disease that uses the Doppler effect to detect the hemodynamic and physiological parameters of the major intracranial basilar arteries. It can provide important hemodynamic information that cannot be measured by other diagnostic imaging techniques for cerebrovascular disease. And the result parameters of TCD ultrasonography such as blood flow velocity and beat index can reflect the type of cerebrovascular disease and serve as a basis to assist physicians in the treatment of cerebrovascular diseases. Artificial intelligence (AI) is a branch of computer science which is used in a wide range of applications in agriculture, communications, medicine, finance, and other fields. In recent years, there are much research devoted to the application of AI to TCD. The review and summary of related technologies is an important work to promote the development of this field, which can provide an intuitive technical summary for future researchers. In this paper, we first review the development, principles, and applications of TCD ultrasonography and other related knowledge, and briefly introduce the development of AI in the field of medicine and emergency medicine. Finally, we summarize in detail the applications and advantages of AI technology in TCD ultrasonography including the establishment of an examination system combining brain computer interface (BCI) and TCD ultrasonography, the classification and noise cancellation of TCD ultrasonography signals using AI algorithms, and the use of intelligent robots to assist physicians in TCD ultrasonography and discuss the prospects for the development of AI in TCD ultrasonography.

Robust Frequency Domain Spline Adaptive Filtering Based on the Half-Quadratic Criterion: Performance Analysis and Applications

Frequency domain spline adaptive filters (FDSAF) have attracted a great deal of attention because of their enhanced computational efficiency. However, their performance will be extremely degraded in practical environments where non-Gaussian phenomena exist. In order to attain good robustness to non-Gaussian noises while ensuring a low computational burden, this paper proposes a frequency domain spline adaptive filtering algorithm based on the half-quadratic criterion (HQC), named FDSAF-HQC. Further, to offer a theoretical foundation for the proposed FDSAF-HQC, a detailed performance analysis based on the principle of energy conservation is conducted and then validated by simulations. Moreover, the computational complexity of FDSAF-HQC is evaluated and compared with other similar algorithms. Simulation results of nonlinear system identification corroborate the outstanding performance of the proposed FDSAF-HQC, i.e., better robustness and computational efficiency. The superiority of the proposed FDSAF-HQC is also supported by practical applications of echo cancellation and biological signal denoising.

An improved signal detection algorithm for a mining-purposed MIMO-OFDM IoT-based system

&lt;abstract&gt; &lt;p&gt;The coal mine internet of things (IoT) communication system is used for real-time monitoring of mining production to ensure the safety and reliability of personnel and equipment in the mine. To eliminate multipath fading in the process of wireless communication in mines, multiple-output multiplexing (MIMO) and orthogonal frequency division multiplexing (OFDM) technologies are introduced. In this paper, a wireless communication system architecture of IoT in mining based on MIMO-OFDM is constructed. Aiming to solve the problems of intersymbol interference and frequency selective fading at the receiver, an improved minimum mean square error ordered successive interferences cancellation (MMSE-OSIC) signal detection algorithm is proposed. First, the signal-to-interference plus noise ratio of the received signal is calculated and the calculation results are sorted. The lowest signal-to-noise ratio is selected as the weakest signal layer. Then, the MMSE-OSIC algorithm is used to extract all of the signals, except the weakest layer. Finally, a maximum likelihood (ML) algorithm is used to traverse the whole signal domain; the signal symbol with the smallest distance from the weakest signal layer is found as the original signal of the weakest signal layer, and it is combined with the signal detected by MMSE-OSIC; then, the final signal detection result is obtained. The simulation results show that, compared with three benchmark algorithms, the proposed MMSE-OSIC algorithm has better signal detection performance under the conditions of different modulation methods and different channel numbers.&lt;/p&gt; &lt;/abstract&gt;

A Phase-Locked Loop With Inherent DC Offset Rejection for Single-Phase Applications

In this article, we aim to design a simple dc immune phase-locked loop (PLL) for single-phase applications. The dc offset is inherently rejected using only two delay operators. The dc offset in the synchronization unit is a challenging problem that causes oscillation in the estimated grid information. Using conventional filters to solve this problem is ineffective since this degrades the synchronization unit's dynamic performance. Different PLLs have been introduced in this article to mitigate the dc offset. Each has its merits and demerits, such as complex structure, high computational burden, and slow transient response. The proposed PLL incorporates two cascaded delayed signal cancellation operators with an arbitrary-length time delay, rejects the dc offset, and perfectly synchronizes with the grid. This article also presents a small-signal model to facilitate the loop filter design and stability analysis. Besides the simulations, the PLL's performance is validated experimentally under various disturbance conditions, with comparisons with other PLLs.

Interference Alignment for Physical Layer Security in Multi-User Networks With Passive Eavesdroppers

We investigate the physical layer security (PLS) in multi-user interference networks. In particular, we consider secure transmission from a legitimate source (Alice) to a legitimate destination (Bob), coexisting with multiple passive eavesdroppers (Eves), as well as multiple legitimate transceivers. By assuming that only statistical channel state informations (CSIs) of Eves and local CSIs of legitimate users are available, we propose an artificial noise (AN) assisted interference alignment (IA) for security enhancement. Unlike traditional IA based security approaches which may result in secret signal cancellation, we design a modified alternating minimization (AM) scheme to overcome this threat, by incorporating the max-eigenmode beamforming (MEB) for secure transmission. Moreover, by partitioning the IA equation into three independent subsets and their combinations, a much tighter necessary condition for IA feasibility is established. We also provide guiding insights into the practical system designs, including useful guidelines for the selection of the dimension of AN. Furthermore, the power allocation ratio between the secret signal and the AN signal is optimized to minimize the secrecy outage probability (SOP), subject to a minimum secrecy rate constraint. Numerical results demonstrate that our design can enhance both quality and security of the secret signal, and thus is suitable and reliable for PLS in interference networks.

MMIC GaAs Isolators and Quasi-Circulators With Co-Designed RF Filtering Functionality

This paper reports on the RF design and practical development of GaAs MMIC multi-functional RF isolators and quasi-circulators with embedded filtering functionality. They are based on cascaded arrays of non-reciprocal resonators (NRRs), passive resonators, and impedance inverters. A unique transistor-based architecture is used for the realization of the NRR that exhibits an one-pole type bandpass response in the forward direction and RF signal cancellation in the reversed one. By controlling the number and type of resonators within cascaded resonator arrays, different levels of gain, out-of-band selectivity and in-band isolation can be obtained. The operating principles of the multi-functional isolator/filtering and quasi-circulator/filtering concepts are presented through synthesized and linear circuit-simulated examples. Practical design aspects using a commercially available GaAs MMIC process are also discussed. For proof-of-concept demonstration purposes, four prototypes were designed and experimentally validated at X-band. They include: i) a NRR, ii) a two-resonator based frequency selective isolator (FSI), iii) a five-resonator based FSI, and iv) a two-pole/two-TZ frequency selective quasi-circulator (FSQC).