Active Cancellation Technique Research Articles

Low-Scattering-Cross Section Thinned Phased Array Antenna Based on Active Cancellation Technique

In this article, a novel approach to simultaneously reduce the scattering cross section (SCS) and lower sidelobe level (SLL) as well as the cost of a phased array is proposed, which is a combination of active cancellation and array thinning techniques. Two 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times\,\,10$ </tex-math></inline-formula> planar microstrip phased arrays are designed to validate the proposed concept, including a full array and a thinned array with 20 passive elements. In the thinned array, the passive elements are made use of and terminated at an optimized position with short-circuited loads to generate scattering fields with the required magnitude and phase for cancellation of the scattering fields from the active elements. Furthermore, the positions of the passive elements are optimized by a multiple dimensional discrete particle swarm optimization (MDDPSO) algorithm to achieve a low SLL. It is theoretically predicted that the thinned array features a low SLL below −18 dB in a scan range of ±45°, and SCS reductions of 21 and 9.1 dB in 7.3–10.1 GHz compared to an equal-sized metallic plate and a full array, respectively, which are further verified in simulations and measurements. It is also remarkable that the array cost is reduced due to array thinning, at the cost of an approximately 1 dB gain drop.

Wideband, Millimeter Wave Domain SI Canceling (&gt;50dB) In-Band Full-Duplex Circulator Receiver

This paper describes a 26-GHz fully integrated In-band Full-duplex Circulator (IBFD) Receiver (RX), which employs passive and active Self-interference Cancellation (SIC) techniques in the mm-wave domain. Coverage of wireless networks at mm-wave frequencies can be enhanced by deploying a large number of base stations economically based on Integrated Access and Backhaul (IAB) relays and repeaters. However, to retain the channel capacity, IAB needs to be implemented using full-duplex schemes that suffer from a strong Transmitter (TX) to RX SI. This SI leakage can significantly impact the receiver sensitivity and increase the baseband/ADC dynamic range requirements. Canceling SI at mm-wave applications is particularly challenging given the high frequency of operation, wide bandwidth, and antenna (ANT) impedance sensitivity to the surroundings. Proposed mm-wave RX with a shared ANT interface based on a circulator with active SI cancelers provide ~53 dB SIC over 400 MHz and ~40 dB SIC over 400 MHz in mm-wave domain to meet the link budget requirements. Proposed architecture achieves SIC by (i) introducing a shared ANT interface based on a hybrid-coupler and a non-reciprocal delay line that provides wideband SIC and additionally creates a SI replica (ii) subsequent active cancellation using SI replica processed with variable gain amplifiers and phase shifters. This system also accommodates SI channel variations due to surroundings. Proposed 26-GHz circulator RX has >100x better SIC at high TX power (>10dBm) levels in comparison to the state-of-the-art and it consumes ~111 mW power. The system is implemented in 45nm SOI CMOS and has an active area of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$4.54\, mm^{2}$ </tex-math></inline-formula> . Stand-alone RX NF is ~5.8 dB and TX to ANT insertion loss (IL) is ~3.1 dB. Over-the-air measurements with modulated TX (128 QAM 2.1 Gb/s) and RX (128 QAM 4.2 Gb/s) signals show an EVM of 3.3%.

Dual Feeding Antenna for Performance Enhancement of Next Generation of Mobile Networks against Self Interference

Actually, the interference phenomena appear in all current wireless communication systems. Generally, conventional wireless communication systems use two separate channels; one of them for transmitting and the other one for receiving. Achieving single channel full duplex (FD) represents one of the key challenges for the implementation of 5G. Single channel FD permits the capability of wireless communication system to transmit and get concurrently on the identical channel, as well as the assurance of an efficient utilization of the current spectrum. With this newest technology, another sort of interference, which is called self–interference, will be generated. Therefore, self–interference cancellation strategies have an awesome solution for the development of the next generation. Passive and active cancellation techniques can be used to remedy such type of interference. In this regard, a dual feeding antenna approach is regarded as passive cancellation. This paper is concerned with this type of self-interference cancellation. A patch antenna is simulated and tested for two resonance frequencies; 2.45 and 28 GHz. Both of these frequencies are frequency channel candidates proposed by international telecommunication union (ITU) for the fifth generation of mobile networks.

Investigation of the electrical limit conditions effects in piezoelectric transducer arrays utilized in medical imaging

Crosstalk is considered as an undesirable phenomenon disturbing the electromechanical behavior of the ultrasonic transducer arrays used in medical imaging applications. Indeed, when one element of a transducer array is excited, it generates parasitic voltages and/or displacement fields on the adjacent passive elements. Consequently, these interactions between elements decrease the array’s electroacoustic performance, which affects the obtained image quality. To overcome the crosstalk’s problem, several research works propose active cancellation techniques. In this case, the correction voltages are determined by considering the array’s elements grounded, contrary to the conventional crosstalk’s definition which considers the array elements in Open-Circuit. The novelty of this paper is in one hand the study of the electrical limit conditions’ effects on the physical behavior of a piezoelectric transducer array radiating in a fluid medium (water). On the other hand, a displacement method is proposed to evaluate the crosstalk level when the array elements are grounded. The limitations of the proposed method are also discussed. For this purpose, a piezoelectric transducer array is firstly modeled using a Two-dimensional Finite Elements Method (FEM), when the array elements are not grounded (open-circuit). Then, the results are compared to those obtained when the neighboring elements are grounded (as in the case of the crosstalk’s active cancellation techniques). Finally, measurements are realized on a fabricated transducer array vibrating in air medium and are successfully compared to the results predicted using FEM.

Design of Radiation Hardened Complementary Folded Cascode Amplifier

Sensitive Node Active Charge Cancellation technique (SNACC) is applied on the Complementary Folded Cascode amplifier (CFC) to study single event transients (SET) on this circuit. A Built-In-Detector (BID) is connected to the circuit to sense the variations of the currents in the op-amp and to represent their input and output characteristics. Two circuits are designed with and without SNACC, using UMC_CMOS_180nm process in cadence virtuoso environment. This work analyses to identify the effectiveness of Radiation Hardening By Design (RHBD) technique by comparing radiation sensitive and radiation hardened CFC amplifier.

A Spur-Reduction DC–DC Converter With Active Ripple Cancelation Technique

This paper presents an active ripple cancelation (ARC) technique for reducing the switching harmonics of the output voltage of a dc–dc converter. An ARC module injects an ac current to accurately cancel the inductor current ripple while the switching converter provides the dc output current. As a result, the output spur of the switching converter can be reduced effectively. However, due to the ARC module, the proposed power converter includes two complex poles. To ensure the system stability and achieve accurate ripple cancelation, a proposed control method and an adaptive phase-lock circuit are utilized. Furthermore, the ripple cancelation capability is independent of duty cycle, load current, and other converter parameters. The measurement results demonstrate that the switching spur reduction with ARC technique can achieve 28 dB while the noise floor is kept the same.

Active Cancellation of Self-Interference for Full-Duplex Amplify and Forward Wi-Fi Relay

This letter presents a Wi-Fi compliant self-interference (SI) active cancellation (AC) technique for amplify and forward full-duplex relay (AF-FDR) utilizing orthogonal frequency division multiplexing. First, we describe the system model of AF-FDR, where the relay transparently extends the range of the main access point (AP) to reach a station located outside the AP’s radio coverage. We highlight the SI (and its suppression) impact on FDR, due to simultaneous transmission/reception on the same frequency. We then present a novel Wi-Fi compliant estimation technique of the SI channel and its delay parameters, which are later used for AC, achieving SI suppression of up to an additional 35 dB. The proposed AF-FDR system is simulated in a fading channel environment with Doppler frequency of up to 10 Hz. Simulation results show cancellation gains within 1 dB of static channels with an SI training overhead of 1.5%.

Adaptive Self-Interference Cancellation for Full Duplex Radio: Analytical Model and Experimental Validation

Recent experimental results show that full-duplex (FD) communication is feasible provided that the residual self-interference after cancellation is close to the noise floor. In this paper, we present a low-complexity active self-interference cancellation technique for FD orthogonal frequency division multiplexing (OFDM) systems, which accounts for the inherent cyclostationarity of the OFDM signal in order to effectively cancel the self-interference. The method here proposed estimates the self-interference cancellation path by using a time-averaged mean-square error criterion, combined with a filtered least mean squares adaptive algorithm. Then, its performance is experimentally validated using a self-developed FD radio testbed implemented with off-the-shelf components. When combined with passive cancellation, applying the proposed technique provides enough self-interference suppression as to reach close (less than 2 dB) to the receiver noise floor.

A Low-Power Active Self-Interference Cancellation Technique for SAW-Less FDD and Full-Duplex Receivers

An active self-interference (SI) cancellation technique for SAW-less receiver linearity improvement is proposed. The active canceler combines programmable gain and phase in a single stage and is co-designed with a highly-linear LNA, achieving low noise and low power. A cross-modulation mechanism of the SI canceler is identified and strongly suppressed thanks to the introduction of an internal resistive feedback, enabling high effective receiver IIP3. TX leakage of up to −4 dBm of power is suppressed by over 30 dB at the input of the LNA, with benefits for the entire receiver in terms of IIP3, IIP2, and reciprocal mixing. The design was done in a 40 nm CMOS technology. The system, including receiver and active SI canceler, consumes less than 25 mW of power. When the canceler is enabled, it has an NF of 3.9–4.6 dB between 1.7 and 2.4 GHz and an effective IIP3 greater than 35 dBm.

A Statistical Design Approach Using Fixed and Variable Width Transconductors for Positive-Feedback Gain-Enhancement OTAs

The positive-feedback gain-enhancement operational transconductance amplifier (OTA) design is a promising architecture to scale into deep submicron CMOS. Ever smaller CMOS process nodes require analog circuit designs that can overcome the area–power-matching relation. We introduce a Nauta OTA with a split architecture consisting of fixed width and digitally programmable variable width transconductors utilizing the minimum grid-spacing of the CMOS process enabling an active mismatch cancelation technique. A variation-aware statistical design practice is introduced to analyze the sizing of transconductors, computing code-word solutions for statistically likely solutions, and estimating average maximum dc gain over the entire code-space of many simulated OTAs. Prototypes of a 8-bit differential OTA in 180-nm CMOS designed using the Nauta structure fixed width and digitally programmable variable width architecture achieves an average maximum dc gain of 60 dB, simulated unity gain frequency of 4.6 GHz, and a figure-of-merit of 1 GHz/mW.

Capacitive cancellation technique in design of CMOS low noise amplifier for ultrasound applications

In this paper active capacitive cancellation technique, is proposed for alleviating the side effects of the parasitic capacitance of the ultrasound piezoelectric probe and cable. This parasitic capacitance imposes a low frequency pole at the input of the circuit, which deteriorates the noise and the transient response of the circuit, crucial parameters for ultrasound imaging systems. Employing a capacitor in a positive feedback loop of a well-defined gain amplifier actively cancels the parasitic capacitance at the input of the amplifier. Making use a binary weighted capacitor bank keeps the circuit safely away from the instability problems due to the variations of process and corner cases. For verification of the proposed technique, the circuit was designed and simulated in a 0.18 µm, 1.8 V CMOS technology. Simulation results show that this technique for equal power consumption presents a better noise performance and more than 100% higher bandwidth compared to the conventional active resistive termination approach.

Active and Passive Self-Interference Cancellation Techniques for Full-Duplex Systems in the Next Generation (5G) of Mobile Communication Networks

Fifth Generation of cellular networks is coming in the next few years and we think that it will not be predicted as a development version of the existing one. The wireless research community aspires to visualize full duplex operation by supporting concurrent transmission and reception in a single time/frequency channel for the sake of improving the attainable spectral efficiency by a Factor of two as compared to the family of conventional half duplex wireless systems. The main challenge encountered in implementing full duplex wireless devices is that of finding techniques for mitigating the performance degradation caused by self-interference. Self-interference suppression will represent one of the main merits that offered by the Fifth Generation Networks. While in the existing version of mobile networks the available spectrum is not sufficiently used, the predicted version will use that spectrum in more efficient manner in such a way that it will be approximately full all the operating time. The object of this paper is to scan the existing techniques that are concerned with Self Interference cancellation on the level of antenna and system design to allow us to suggest some solutions for that problem in the future.

All-Digital Self-Interference Cancellation Technique for MIMO Full-Duplex Systems

In this paper, the MIMO full-duplex system is proposed to remove self-interference signal using modified DFT based channel estimation technique. In SISO full-duplex systems only single transceiver can transmit data on either side simultaneously whereas in MIMO full-duplex systems multiple transceivers can transmit data simultaneously from both sides. During MIMO full-duplex transmission selfinterference and circuit impairments may occur, to avoid such noises digital cancellation technique is used which is a lowest complexity self-interference cancellation technique in all fullduplex systems. In this technique receiver auxiliary chain and its copy circuit called ordinary receiver chain is used to cancel out the both self-interference and its circuit impairments. Noise added during wireless channel is suppressed by using passive suppression technique and Gaussian noise, phase noise and quantization noise is eliminated by the active cancellation technique. So, combination of active cancellation and passive suppression techniques are used to eliminate the circuit impairments. The proposed channel estimation technique is used to cancel out the self-interference produced at the output of both auxiliary and ordinary receiver chains. By using digital self-interference cancellation technique the amount of self-interference cancelled is 37dBm higher than the receiver noise floor. The achievable rate and throughput of MIMO full-duplex system is 28 bits/sec/Hz and 1049.04 Mbps respectively which is very large when compared to MIMO half-duplex , SISO full-duplex and SISO half-duplex systems. General Terms QAM, OFDM, Modified DFT based channel estimation, Digital cancellation.

Flexure-based dynamic-tunable five-axis nanopositioner for parallel nanomanufacturing

With the increasing demand for devices and systems with nanometer precision in the modern manufacturing industry, tip-based nanofabrication (TBN) has become an indispensable part of manufacturing process. However, a common issue that needs to be addressed is to increase the throughput of TBN, which is sequential and inherently slow. To overcome the difficulty, in this paper we present the design and control of a flexure-based five-axis nanopositioner with dynamic-tuning capability for parallel nanomanufacturing applications. The dynamic-tuning method enables trade-offs between the range and speed of the nanopositioner so as to increase the throughput of the nanomanufacturing system. The experimental results indicate that the nanopositioner conforms with the in-plane range and resolution requirements, i.e., ±5mm/100nm in X/Y axis, while its natural frequencies in X/Y axis can be increased by two to three times at the expense of decreased stroke, i.e., elastic range. In addition, real-time dynamic-tuning experiments show active vibration cancellation techniques can be implemented on the nanopositioner and effectively eliminate the unwanted dynamics and improve the overall dynamic performance. Lastly, we performed nano-scratching experiments using an 18 tip AFM array to fabricate optical grating patterns on gold coated silicon substrates of 5×1mm2 to demonstrate the practicality of the new method. The experiment confirmed good parallelism had been achieved during the experiments, where the scratched gold lines have a consistent depth of ∼160nm.

Parameter Estimation of Linear-FM with Modified sMLE for Radar Signal Active Cancelation Application

This study examined a radar signal active cancelation technique, which is a theoretical way of achieving stealth by employing a baseband process that involves sampling the incoming hostile radar signal, analyzing its characteristics, and generating countermeasure signals to cancel out the linear-FM signal of the hostile radar signal reflected from the airborne target. To successfully perform an active cancelation, the effects of errors in the countermeasure signal were first analyzed. To generate the countermeasure signal that requires very fast and accurate processing, the down-sampling technique with the suboptimal maximum likelihood estimation (sMLE) scheme was proposed to improve the speed of the estimation process while preserving the estimation accuracy. The simulation results showed that the proposed down-sampling technique using a 2048 FFT size yields substantial power reduction despite its small FFT size and exhibits similar performance to the sMLE scheme using the 32768 FFT size.

ACTIVE SELF INTERFERENCE CANCELLATION TECHNIQUES IN FULL DUPLEX COMMUNICATION SYSTEMS - A SURVEY

In this paper we present a survey based on vast res earch done in the area of various important factors relating to full duplex communication revealing several facts. In fact thes e revelation has served to be vital in the future d esign of any full duplex communication system . The major problem or challen ge faced in such a system was the interference caus ed from the transmitting antenna on the receiver antenna placed at the same node. The interference was termed as ' self interfe rence'. Wireless transceivers nodes can select between transmit and receive funct ions on the same frequency band at different time ( Time Division Duplex-TDD) or they can transmit at the same time at different frequencies ( Frequency Division Duplex-FDD). Recen tly researchers have put forth a new radio system, that can operate full duplex ov er a single channel , that is transmitting and rec eiving at the same time on the same frequency band. This kind of system is overwhe lmed by interference. Interference need to be redu ced to the point where the receiver can detect even the weakest signal of inte rest. Several active interference cancellation tech niques that can help in self interference reduction have been proposed. The in d epth survey was helpful enough to come out with a n ovel solution to an antenna design based on passive suppression techniques usin g polarization and other diversity techniques so a s to reduce the self interference problem.

An Active Cancellation Circuit for Reducing Electrical Noise from Three-Phase AC Motor Drivers

A novel active cancellation circuit for reducing common-mode (CM) noise in vehicular three-phase ac motor drives is described. The cancellation circuit features a feed-forward voltage-detecting-voltage-compensating structure. Unlike other voltage-compensating circuitry employing CM transformers on the thick phase wires, the proposed circuit is compactly integrated on the inverter printed circuit board. A prototype low-voltage space-vector-pulse-width-modulation (SVPWM) inverter employing this active cancellation technique was built and tested. This cost-effective and light-weight circuit significantly reduced the CM noise at the fundamental switching frequency and harmonics up to 2 MHz.

Single-Event-Hardened CMOS Operational Amplifier Design

Novel RHBD techniques are described that utilize charge sharing to mitigate single-event voltage transients in a folded cascode operational amplifier. These techniques are analyzed using a new layout aware single-event model with the Cadence Spectre circuit simulator. The techniques are applied in each of the three stages of an operational amplifier (op amp). The sensitive node active charge cancellation (SNACC) technique is applied to the bias circuit and extended to protect multiple sensitive nodes. This technique is shown to provide a 5X reduction in error energy measured at the amplifier output at the cost of increased sensitive area. The differential input stage and the high-gain single-ended cascode output stage of the amplifier are hardened using differential charge cancellation (DCC) layout techniques that promote charge sharing. These hardening techniques are shown to provide up to orders of magnitude reductions in single-event error energies as measured at the op amp output and reductions in sensitive area of more than 15% across all LETs simulated.

Experiment-Driven Characterization of Full-Duplex Wireless Systems

We present an experiment-based characterization of passive suppression and active self-interference cancellation mechanisms in full-duplex wireless communication systems. In particular, we consider passive suppression due to antenna separation at the same node, and active cancellation in analog and/or digital domain. First, we show that the average amount of cancellation increases for active cancellation techniques as the received self-interference power increases. Our characterization of the average cancellation as a function of the self-interference power allows us to show that for a constant signal-to-interference ratio at the receiver antenna (before any active cancellation is applied), the rate of a full-duplex link increases as the self-interference power increases. Second, we show that applying digital cancellation after analog cancellation can sometimes increase the self-interference, and thus digital cancellation is more effective when applied selectively based on measured suppression values. Third, we complete our study of the impact of self-interference cancellation mechanisms by characterizing the probability distribution of the self-interference channel before and after cancellation.

High Bandwidth Control of Ball Screw Drives

This paper presents a tracking control strategy for high speed ball screw drives. Rigid body motion is controlled using adaptive sliding mode control. Torsional vibrations are modeled, experimentally identified, and compensated in the control law using notch filtering and active cancellation techniques. Attenuation of torsional resonances improves the stability margins and enables high positioning bandwidth to be achieved. The axis friction is experimentally identified and cancelled out in feedforward, in order to improve the positioning accuracy at motion reversals. The developed control law is verified experimentally on a high speed ball screw drive, where a tracking accuracy of 1.6 um is maintained while traversing the axis at 1000 mm/sec feed and 1 g acceleration.