Radio Frequency Receiver Research Articles

RF low power subsampling architecture for wireless communication applications

With the increasing demands of wireless communication, flexible, complex, and diversified wireless communication applications are required. However, the difficulty of enabling new wireless communication applications is the lack of low power radio frequency (RF) transmission devices, especially the RF receiver. In order to alleviate this problem, an RF low power subsampling architecture for wireless communication applications is proposed in this paper. This subsampling architecture adopts a single-ended to differential configured balun low noise amplifier (balun-LNA), a subsampling mixer with high sampling ratio and a finite input response (FIR) filter and infinite impulse response (IIR) filter achieving frequency down-conversion, avoiding using high power-hungry blocks. Based on a subsampling theory, an optimum sampling frequency for the subsampling architecture is necessary to relax the complexity of the system. For the application of internet of things (IoT) wireless communication, the paper provides the implementation of the subsampling receiver solutions to get a tradeoff between power consumption, gain, noise, and sensitivity. It can achieve −85 dBm sensitivity for an amplitude shift keying (ASK) modulation at the data rate of 1 Mbps with the clock sampling frequency of 40 MHz. Finally, the theoretical analysis and simulation results show that the performance of the subsampling architecture has several advantages over others.

Low-Power ASK Detector for Low Modulation Indexes and Rail-to-Rail Input Range

A high-performance ultrahigh-frequency amplitude shift keying (ASK) detector for low-power radio-frequency (RF) receivers is proposed. The circuit is based on a high-gain common-source topology with a feedback loop that provides adaptive biasing. Hence, high sensitivity and rail-to-rail input operation are achieved along with low power consumption. The detector was implemented in a standard 130-nm complementary metal–oxide–semiconductor technology. Sensitivity measurements demonstrate correct detection of a 2-Mb/s ASK-modulated 915-MHz signal with a peak level and a modulation index of around 200 mV and 5%, respectively, which means an envelope signal amplitude of as low as 5 mV. The circuit draws less than $3.4 \mu\mbox{A}$ from a 1.2-V power supply while operating with rail-to-rail RF variations and modulation indexes from 5% to 100%. This performance makes the detector suitable for batteryless systems with RF energy harvesting.

Comparison of RF Remote Sensing Vibrometry Focusing on Polarization Mode Dispersion

Common remote-sensing techniques of analyzing received radio frequency (RF) signals, such as amplitude envelope detection and frequency Doppler shift, may work fine when the transmitted RF signal is precisely known and available. But, some remote-sensing applications may not permit such control over the RF transmission. Another technique, RF polarization, offers satisfactory results in some of those situations-when multipath and/or bandwidth-delay spread can be kept low. However, a new technique leveraging the polarization mode dispersion (PMD) inherent in most RF channels promises better results (accuracy, precision, and sensitivity) for most remote-sensing applications. The PMD technique adds a frequency-subband dimension to the analysis that the other methods overlook. This paper will present the data analysis techniques for several methods of RF signal processing aimed at the general remote-sensing application of vibrometry (the measurement of vibrations). Using model simulations calibrated to laboratory results, the PMD-based approach is shown to out-perform more common techniques by one or more orders of magnitude for typical indoor environments. Such performance gains (up to 30 dB on average) could allow for the successful detection of a vibrator or target within an RF field simply by adopting these PMD-based data analysis techniques on the received RF signals.

Analog and RF Interference Mitigation for Integrated MIMO Receiver Arrays

Over the past decade, we have witnessed the maturation of silicon-based phased array technology, which has started to make an impact on commercial and military wireless applications. Over the next decade, driven by the development of next-generation wireless communication networks, we will see the maturation and impact of large-scale multiple-input-multiple-output (MIMO) technology. MIMO receiver arrays exploit digital array signal processing, and consequently are exposed to interference in the analog and radio-frequency (RF) front ends. The absence of analog/RF interference mitigation in traditional digital MIMO receiver arrays results in designs with high-dynamic-range and power-hungry analog and RF receiver front ends and analog-to-digital converters. This paper describes recently developed techniques for spatio-spectral interference mitigation in the analog and RF domain for digital MIMO receivers. The techniques proposed are flexible; tunable across operating frequency; scalable; present low cost, size, and power consumption overheads; and are experimentally validated through a 0.1-1.7-GHz four-element receiver front-end array integrated circuit (IC) prototype in 65-nm complementary metal-oxide-semiconductor (CMOS) technology.

Iterative Dynamic Power Splitting for Multi-relay Networks with Wireless Energy Harvesting

Wireless energy harvesting has attracted a lot of attention in relay networks, where each relay node can use its harvested energy from the received radio frequency (RF) signals to forward messages. In this letter, we consider a multi-relay system and study the problem on how each relay splits the power of its received RF signal to maximize the information signal-to-noise ratio (SNR) at the destination node. As this problem is non-convex and difficult to be solved, we propose an iterative dynamic power splitting algorithm based on analyzing the first order necessary condition of the optimal solution. Besides, the convergence, initial value and transmission protocol of the proposed algorithm are also discussed. Simulation results show that the proposed iterative power splitting algorithm has nearly the same performance as the optimal exhaustive search and outperforms fixed power splitting schemes.

Towards the Realization of Graphene Based Flexible Radio Frequency Receiver

We report on our progress and development of high speed flexible graphene field effect transistors (GFETs) with high electron and hole mobilities (~3000 cm2/V·s), and intrinsic transit frequency in the microwave GHz regime. We also describe the design and fabrication of flexible graphene based radio frequency system. This RF communication system consists of graphite patch antenna at 2.4 GHz, graphene based frequency translation block (frequency doubler and AM demodulator) and graphene speaker. The communication blocks are utilized to demonstrate graphene based amplitude modulated (AM) radio receiver operating at 2.4 GHz.

A Novel Wireless Power Transfer-Based Weighed Clustering Cooperative Spectrum Sensing Method for Cognitive Sensor Networks.

In a cognitive sensor network (CSN), the wastage of sensing time and energy is a challenge to cooperative spectrum sensing, when the number of cooperative cognitive nodes (CNs) becomes very large. In this paper, a novel wireless power transfer (WPT)-based weighed clustering cooperative spectrum sensing model is proposed, which divides all the CNs into several clusters, and then selects the most favorable CNs as the cluster heads and allows the common CNs to transfer the received radio frequency (RF) energy of the primary node (PN) to the cluster heads, in order to supply the electrical energy needed for sensing and cooperation. A joint resource optimization is formulated to maximize the spectrum access probability of the CSN, through jointly allocating sensing time and clustering number. According to the resource optimization results, a clustering algorithm is proposed. The simulation results have shown that compared to the traditional model, the cluster heads of the proposed model can achieve more transmission power and there exists optimal sensing time and clustering number to maximize the spectrum access probability.

Constructing Complete Radio Frequency Receiver for LTE TDD Transceiver

Constructing Complete Radio Frequency Receiver for LTE TDD Transceiver

Active decoupling of RF coils using a transmit array system.

Implementation of a decoupling method for isolation of transmit and receive radio frequency (RF) coils for concurrent excitation and acquisition (CEA) MRI in samples with ultra-short T2*. The new phase and amplitude (PA) decoupling method is implemented in a clinical 3T-MRI system equipped with a parallel transmit array system. For RF excitation, two transmit coils are used in combination with a single receive coil. The transmit coil is geometrically decoupled from the receive coil, and the remaining B 1-induced voltages in the receive coil during CEA are minimized by the second transmit coil using a careful adjustment of the phase and amplitude settings in this coil. Isolation of the decoupling scheme and transmit noise behavior are analyzed for different loading conditions, and a CEA MRI experiment is performed in a rubber phantom with sub-millisecond T2* and in an ex vivo animal. Geometrical (20dB) and PA decoupling (50dB) provided a total isolation of 70dB between the transmit and receive coils. Integration of a low-noise RF amplifier was necessary to minimize RF transmit noise. CEA MR images could be reconstructed from a rubber phantom and an ex vivo animal. CEA MRI can be implemented in clinical MRI systems using active decoupling with parallel transmit array capabilities with minor hardware modifications.

5–35 GHz broadband if amplifier section in 0.13 μm SiGe technology for W‐band heterodyne receiver RFICs

ABSTRACTThis letter presents the results of a broadband intermediate frequency (IF) section radio frequency integrated circuit designed for a W‐band heterodyne radiometer receiver in a 0.13 μm SiGe BiCMOS process. The differential IF section which consists of an amplifier and a power detector uses inductive and resistive matching to obtain a wideband response. The IF amplifier has a measured gain of 10.0–19.5 dB at 2–37 GHz, noise figure of 6–8 dB at 1–26 GHz, and OIP3 of 7–17 dBm at 1–40 GHz. The detector has a measured responsivity of 1 kV/W and an estimated noise equivalent power (NEP) of 4–6 pW/Hz1/2 at 5–35 GHz, respectively. For the IF section, the input return loss is better than 10 dB at 7–40 GHz and the responsivity is 10–82 kV/W at 5–35 GHz. The broadband properties over significantly wider bandwidths than earlier reported silicon‐based IF amplifier and power detector circuits make the SiGe 5–35 GHz IF section suitable for W‐band direct‐conversion radiometer receiver Radio Frequency Integrated Circuits with a larger predetection bandwidth and improved sensitivity. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:2286–2289, 2015

All-Optical Full-Band RF Receiver Based on an Integrated Ultra-High-Q Bandpass Filter

Ultra-broadband radiofrequency (RF) receivers are required in higher frequency-band wireless communications, radar communications or multi-band applications in radio telescopes. Such ultra-broadband receivers are inherently difficult to establish with electronics because of limits in the bandwidth of the devices. Photonic means of RF photonic receivers/frontends can overcome the bandwidth limitation in electrical receivers. One aspect that should be considered is the precise signal processing in the optical domain. Here, a full-band (from the L-band to the W-band) all-optical RF receiver based on the Si3N4 microring filter is proposed and experimentally demonstrated. The resolution and processing range of the filter are lower than 420 MHz and larger than 112.9 GHz (FSR larger than 225.78 GHz), respectively, and the out-band suppression of this filter is greater than 40 dB. The center frequency of the filter can be altered for more than one FSR by tuning the phase-shifter on top of the ring. The performance of the full-band all-optical RF-receiver has been discussed, and the spurious free dynamic range of the receiver from the L-band to the Ka-band (limited by the bandwidth of the modulator in our experiment) has been measured to be larger than 111.6 dB·Hz2/3.

Double‐tuned RF receiver coil for detecting both 1 H and 31 P elements in 4.7 T MRI system

A novel double-tuned radio-frequency (RF) receiver coil for use in magnetic resonance imaging (MRI) systems has been demonstrated based on a birdcage-type circuit. The receiver coil utilises the end-ring current as well as the leg current of the birdcage-type circuit to detect the nuclear magnetic resonance (NMR) signals of different elements simultaneously. It was designed to detect the NMR signals of both 1H and 31P elements in a 4.7 T MRI system. The coil showed an excellent frequency response and provided clear magnetic resonance images of a Na2HPO4 phantom when used with the 4.7 T MRI system.

Designing an ultra-wideband electromagnetic waves receiver with new architecture for RF and wireless applications

This paper demonstrates an electromagnetic waves receiver (EMWR) with new architecture for finding the good performances at the very wide frequency range of 2.8 to 10.8 GHz. The proposed device applies conventional pulse position modulation (PPM) scheme for modulation. The combination of 8th–8th-order derivative of Gaussian pulse is used as impulse received signal. The EMW receiver circuit with core chip dimension of 32 × 10−3 mm2 was modeled in a 90 nm CMOS technology. The output amplitude pulse yielded 200 mV peak-to-peak under a supply voltage of 2.2 V. This circuit consumes 12 pJ/pulse at 0.5 GHz pulse-repeating frequency. The designed device can be employed in the transceiver systems in presence the multipath channel for 2.8 GHz to 10.8 GHz. Results express that the proposed system not only decrease the interference with narrowband (NB) systems, but is also robust against NB interference at the operating frequency of 7 GHz. Regarding to results, the EMWR can be used in radio frequency (RF) and wireless receiver applications.

An Efficient Calibration Scheme for Satellite Onboard Receive Digital Beamformer

ABSTRACTThis paper describes a scheme for faster calibration of satellite onboard receive digital beamformer system consisting of phased array antenna, receive radio frequency (RF) electronics, and digital beamforming processor. In antenna arrays with a large number of antenna elements, the required number of measurements for the characterization of the antenna array is demanding. A computationally efficient calibration method, suitable for applications like LEO satellite tracking, deep space mission, very large phased array telescopes etc., wherein the requirement is for both fast and accurate calibration is described in this paper. The simulation results for 30-elements triangular phased array antenna based receive digital beamformer at different signal-to-noise ratios are presented. This calibration method is applicable to arbitrary topology of phased array antenna.

Wireless information and power transfer in two-way relaying network with non-coherent differential modulation

In this paper, we consider a denoise-and-forward (DNF) two-way relay network (TWRN) with non-coherent differential binary phase-shift keying modulation, where a battery-free relay node harvests energy from the received radio frequency (RF) signals and uses the harvested energy to help the source nodes for information exchange. Based on the power splitting (PS) and time switching (TS) receiver architectures, power splitting relaying (PSR) and time switching relaying (TSR) protocols at relay are studied. In order to investigate the effect of power allocations on two source nodes, power splitting coefficient and time switching factor at relay on performance, the two proposed protocols are analyzed and the bit error rate (BER) expressions of end-to-end system are derived. Based on these expressions, the optimal power of sources, the power splitting ratio and the time switching factor are obtained via the numerical search method. The simulation and numerical results provide practical insights into the effect of various system parameters, such as the power splitting coefficient, the time switching factor, sources to relay distances, the noise power, and the energy harvesting efficiency on the performance of this TWRN. In addition, the results show that the PSR protocol outperforms the TSR protocol in terms of throughput under various network geometries.

InPutter: an engineered putter for on-the-fly golf putting analysis

This paper presents the development and experimental assessment of an engineered putter, denoted as InPutter. InPutter was designed for research, analysis and training, so as to improve the performance of the golf putting. The device has the same physical properties of a common putter club, thus keeping its ecological validity and being ideal for both novice and expert players. The engineered putter is equipped with an inertial measurement unit, force sensitive resistors and heartbeat radio-frequency receiver compatible with Polar electrocardiogram transmitters. All these are connected to an internal CPU with WiFi technology that allows retrieving all golf putting process variables, in real-time, at a high frequency of 100 Hz. As an internet-connected product, all data can be analyzed on-the-fly using a common interface connected to the cloud (e.g. laptop or smartphone). The putter is battery operated and able to keep an autonomy of up to 4 h, ideal for both Pitch & Putt and traditional Golf games, with a...

Anefficient quadrature demodulator for medical ultrasound imaging

Quadrature demodulation is used in medical ultrasound imaging to derive the envelope and instantaneous phase of the received radio-frequency (RF) signal. In quadrature demodulation, RF signal is multiplied with the sine and cosine wave reference signal and then low-pass filtered to produce the base-band complex signal, which has high computational complexity. In this paper, we propose an efficient quadrature demodulation method for B-mode and color flow imaging, in which the RF signal is demodulated by a pair of finite impulse response filters without mixing with the reference signal, to reduce the computational complexity. The proposed method was evaluated with simulation and in vivo experiments. From the simulation results, the proposed quadrature demodulation method produced similar normalized residual sum of squares (NRSS) and velocity profile compared with the conventional quadrature demodulation method. In the in vivo color flow imaging experiments, the time of the demodulation process was 5.66 ms and 3.36 ms, for the conventional method and the proposed method, respectively. These results indicated that the proposed method can maintain the performance of quadrature demodulation while reducing computational complexity.

Enhanced RF to DC converter with LC resonant circuit

Presented in this paper is an experimental comparison of the conventional and proposed design circuit of a radio frequency (RF) energy harvesting. RF to DC energy harvester simply consists of antenna and rectifier block for receiving electromagnetic radiation signal and to produce a DC voltage, respectively. In addition to this conventional circuit, the proposed design includes LC tank circuit as receiving block of a well-designed antenna radio frequency receiver. Proper choice of an antenna type, realizing of point contact Germanium diodes as rectifier and correct design values for the LC passive components, greatly improved the measurement of the maximum output power, giving approximately a 100% increase compared to the conventional method. Experimental results of the enhanced RF to DC converter measured a maximum output power of 1.80 mWat a distance of 77.84 meters from a TV signal tower operating at 165 MHz.Thus, the harvested signal was enough to supply a low power wireless device applications without battery maintenance.

A Continuous-State Reinforcement Learning Strategy for Link Adaptation in OFDM Wireless Systems

This paper presents a machine learning approach based on the concept of reinforcement learning andMarkov Decision Processes for link adaptation in orthogonal frequency-division multiplexing systemsthrough adaptive modulation and coding. Although machine learning techniques have attracted attentionfor link adaptation, the schemes proposed so far are based on off-line training algorithms, which makethem not well suited for real time and real-world operation. The proposed solution learns the bestmodulation and coding scheme for a given signal-to-noise ratio by interacting with the environment(the radio channel). Unlike the other solutions, it does not rely on an off-line and computationallyintensive training phase. Simulation results show that the proposed technique outperforms the wellknownsolution based on look-up tables for adaptive modulation and coding, and it can potentiallyadapt itself to distinct characteristics of the environment or the receiver radio frequency (RF) front end.

Vehicle Locking Using Radio FrequencyIdentification with Theft Intimation and Smart Tracking System

This paper presents the use of Radio Frequency Identification for locking the vehicle; along with vehicle theft intimation and smart tracking system. The present vehicle locking systems consists of; mechanical lock and key architecture or Remote Keyless Entry (RKE) architecture. The vehicle intruders can easily gain the access of the vehicle by duplicating keys, breaking mechanical locks and use radio frequency receivers with appropriate decryption algorithms in case of Remote Keyless Entry (RKE) architecture. Moreover, there isn‟t any provision for remotely communicating with the vehicle for tracing. The proposed system consists of using Unique Radio Frequency Identification cards along with password authorization for locking the vehicle. The driving license number issued by RTO‟s can be used for Unique Radio Frequency Identification along with password verification to unlock the vehicle and its ignition. Thus protecting the vehicle from intruders. Perhaps, this will also make the use of license mandatory to drive the vehicle. This project also involves a provision for theft intimation to the owner of the vehicle in the form of a call from the GSM module fixed in the vehicle. As soon as, the intruder will open the bonnet of the vehicle to start the ignition; which otherwise is not possible; the bonnet switch is open circuited and a call is initiated to the owners cellphone and GPS co-ordinates are continuously sent as SMS. Thus, vehicle‟s route can be easily traced on the Google maps.