Wideband Transceiver Research Articles

On the General Mathematical Framework, Calibration/Compensation Method, and Applications of Non-Ideal Software Defined Harmonics Rejection Transceivers

Recently harmonic interference rejection has been recognized as a crucial bottleneck of truly wide-band software defined radio transceivers. Phase and gain mismatches among mixing paths, typical for nanoscale technology nodes, severely impact the achievable rejection ratio in classical harmonic rejection transceivers. This paper proposes an alternative digital intensive architecture, which enables increased harmonic interference rejection for wide-band SDR transceivers impacted by severe gain and phase mismatches. A generic mathematical framework of the target architecture is introduced to support a systematic design space exploration for multi-path harmonic interference rejection transceivers. With the framework, an iterative on-die estimation and compensation of mismatch for both the transmitter and receiver are presented. Case study with four mixing paths shows that ideal rejection can be achieved when targeting a single dominating harmonic interferer, and joint suppression of the 3rd and 5th order harmonic interferers of at least 70 dB can be obtained under realistic radio input scenarios.

Microwave System to Detect Traumatic Brain Injuries Using Compact Unidirectional Antenna and Wideband Transceiver With Verification on Realistic Head Phantom

A portable microwave system to detect traumatic brain injuries is described. The wideband system utilizes a unidirectional antenna, microwave transceiver, and processing and image reconstruction algorithms. The utilized antenna is designed to have a compact three-dimensional (3-D) structure using a slotted dipole element and a folded parasitic structure. It attains directional radiation patterns with an average 9-dB front-to-back ratio and 102.2% fractional bandwidth covering the band 1.1–3.4 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$~$</tex> </formula> GHz, which is suitable for head imaging. To test the system, a realistic head phantom, which attains accurate internal and external anatomical structure and electrical properties, is fabricated by a 3-D printer using a detailed numerical model. Targets imitating the properties of bleeding are inserted at different positions in the fabricated head phantom to emulate brain injury scenarios. The integrated system is used in a virtual arrayed monostatic radar approach to detect the injuries. Using data sets recorded at 32 antenna positions around the head, a back projection algorithm is used to generate images of the scanned head. The achieved results demonstrate the feasibility of such a system as a portable module for brain injuries detection.

3–10 GHz ultra wideband front‐end transceiver in 0.13 μm complementary metal oxide semiconductor for low‐power biomedical radar

A new integrated low-power, low-complexity ultra wideband (UWB) transceiver front-end in standard 130 nm complementary metal oxide semiconductor technology which can be used in UWB radar biomedical sensing applications is proposed in this study. The transceiver comprises of a full UWB band transmitter, an on-chip diplexer and a full UWB band receiver front-end. The transmitter generates Gaussian-pulse-modulated and rectangular-pulse-modulated signals at different carrier frequencies within the designated UWB by using a digitally controlled oscillator. The transmitter consumes an average power of 8 mW at a 10 MHz pulse rate. The on-chip diplexer has a 1 dB insertion loss and an isolation of −30 dB. Its switch is co-designed with the receiver's input matching network to optimise the power matching while achieving good noise performance. The receiver low noise amplifier has a 3–10 GHz input matching bandwidth with a power gain of 16 dB. The overall receiver front-end consumes an average power of 12 mW. The core area of the transceiver circuit is 500 μm by 1100 μm. The experiments show that the proposed radar transceiver can successfully detect a human respiration pattern within 50 cm. This novel design using a DCO-type UWB transceiver integrated with an on-chip diplexer demonstrates the use of the low power UWB radar detection in biomedical applications.

Reconfigurable LNA for MB-OFDM Receiver using Active Inductor

Low Noise Amplifier (LNA) is very much important in achieving good reception sensitivity in the wideband transceiver of Ultra Wide Band (UWB) architecture. In this paper, the LNA is designed for Multi Band-Orthogonal Frequency Division Multiplexing (MB-OFDM) receiver, which is used to transmit the information on 14 different sub bands of UWB with minimum of 528 MHz frequency in each band. The LNA comprises of three stages namely input stage, core stage and output stage. The input stage is for better Input matching and output stage contributes better Output matching by acting as a buffer. The core stage is responsible for high gain of the LNA. Different sub bands are achieved with the help of inductors at the input and the output stage. The spiral inductor at the input stage of the LNA is replaced with a suitable active inductor. The gain and Noise Figure of all the three stages depends on the Active inductor. The gain of the Active Inductor (AI) based LNA varies from 25 dB to 22 dB throughout the 14 bands of UWB. The noise figure varies from 5 dB to 6.3 dB. The input impedance lies between -7 dB to -9 dB and output impedance lies from -5 dB to -14 dB. All simulations are carried out using Advanced Design Software (ADS) 2013.

Ultra Wideband Transceivers Based on Chaotic Pulses and their Application to Wireless Body Area Networks

Ultra Wideband Transceivers Based on Chaotic Pulses and their Application to Wireless Body Area Networks

Performance Evaluation of WideMac Compared to ALOHA in term of Energy Consumption for IR-UWB based WSN

The introduction of the IR-UWB Technology in the field of WSN was promising for researchers especially for its low power consumption feature. To implement such a solution, we need a suitable MAC protocol to exploit the specific features of this technology. When introducing this Technology, ALOHA was the only candidate MAC protocol. Because of the high energy consumption of ALOHA, in this paper we present WideMac, a low power medium access control protocol designed specifically for Impulse Radio Ultra Wide Band transceivers. The IR-UWB channel offers ultra low power transmissions and unmatchable robustness to multiple access interference. WideMac takes advantage of these two key properties by using asynchronous periodic beacon transmissions from each network node. To test and evaluate the performance of WideMac protocol we used PhyLayerUWBIR class developed under MiXiM platform on OMNet++ as a physical layer. For the MAC layer we developed our own class WideMacLayer.

A Reconfigurable FM-UWB Transceiver for Short-Range Wireless Communications

A 3.7-4.3 GHz frequency modulated ultra wideband (FM-UWB) transceiver with digitally reconfigurable subcarrier modulation index, UWB bandwidth and RF frequency band is fabricated in 0.18 μm CMOS. Considering short-range low-data-rate applications for wireless body area networks, RF front ends, consisting of an output amplifier with -14 dBm power level, an FM demodulator with -35 dBm sensitivity, and a preamplifier with 25 dB gain, 6 dB noise figure, are designed. The presented implementation including UWB bowtie antennas achieves a bit error rate (BER) of 10-6 at a data rate of 12.5 kb/s with a wireless communication distance of 60 cm and the power dissipation of 21 mW.

A Survey on FM-UWB Transceivers

his paper surveys the research on frequency modulated ultra- wideband (FM-UWB) transceivers. FM-UWB system uses low modulation index digital FSK followed by high modulation index analog FM to generate a constant envelope UWB signal with a flat power spectral density and steep spectral roll-off. FM-UWB can be seen as an analog implementation of a spread spectrum system with spreading gain equal to the modulation index. FM-UWB system is suitable for low data rate and short-range applications. The advantages of FM-UWB system such as low power consumption, very low radiated power (−41.3 dBm/MHz), good coexistence with other existing wireless technologies, and robustness to interference and multipath making it suitable for Wireless Body Area Network (WBAN) in medical applications.

A SIMO one-bit time reversal for UWB communication systems

With the one-bit time reversal ultra wideband (OTR-UWB) transceiver, the data symbols are encoded using the reversed order of the channel phase. The major factor limiting SISO OTR capacity and performance is intersymbol interference (ISI). As the data rate goes up, the ISI becomes more severe and it degrades system performance and capacity. In this article, a new single input multiple output (SIMO) system is proposed for an OTR-UWB system. The proposed transceiver structure is based on spatial focusing property of OTR. The performance of the proposed SIMO OTR-UWB system is analyzed in terms of the signal-to-interference-plus-noise-ratio (SINR). It is shown that using a SIMO OTR transceiver, ISI is reduced and the system capacity is increased almost linearly with the number of received antenna. Transmitted signal power at SIMO OTR decreases therefore in low data rates, SISO performance is better than SIMO, but in high rate scenario, SIMO OTR suppresses ISI better than SISO OTR and its performance is better. It is possible to compensate the reduced power using a receiver with more sensitivity, but to compensate the ISI effects, an MMSE receiver or equalizer techniques should be used, since the computational complexity of MMSE receiver grows exponentially with channel length and equalizers reduce the efficient bit rate. It is shown that the proposed SIMO-OTR capacity linearly increases with the number of antennas and decreases logarithmic (almost linearly).

KEY DESIGN PARAMETERS AND SENSOR-FUSION FOR LOW-POWER WEARABLE UWB-BASED MOTION TRACKING AND GAIT ANALYSIS SYSTEMS

Recently, we proposed a wireless ambulatory gait analysis system that provides a high ranging accuracy using ultra- wideband (UWB) transceivers. In this paper, we further investigate the performance of our proposed system including ranging using suboptimal templates, power consumption, and sensor-fusion. We show that the proposed system is capable of providing a 1.1mm ranging accuracy (11.7mm for current systems) at a signal-to-noise-ratio (SNR) of 20dB using suboptimal-based receivers in industry accepted body-area-network UWB channels. For the angular-displacement, our system provides an accuracy that is less than 1 - for the knee- ∞exion angle. This accuracy is superior to the accuracy reported in the literature for current technologies (less than 4 - ). Finally, we propose the integration of UWB sensors with force sensors. The system performance and design parameters are investigated using simulations and actual measurements. Ultimately, the proposed system is suitable for taking accurate measurements, and for tele-rehabilitation.

ON BODY CONCEALED WEAPON DETECTION USING A PHASED ANTENNA ARRAY

The detection and identiflcation of metal items and, in particular weapons, of linear size ‚ 10cm, concealed upon the human body, is demonstrated as being entirely feasible by using a phased array of suitably ultra wide band transceivers. The complex natural resonances and especially the fundamental resonance, are excited by ultra wide band, stepped frequency continuous wave illumination of the target, using a phased array of antennae to focus the radiation. Broadband illumination of the target with microwave radiation of suitable frequency range (Typically 0.3{3GHz for handgun sized objects) excites low order complex natural resonances and the late time response of the concealed item can be spatially located using phased array imaging techniques. Further processing of the late time response enables classiflcation of the concealed object, based on the complex natural resonant frequencies of the object, so that threat items such as handguns and knives can be difierentiated from benign items such as mobile phone handsets and cameras.

Linearization Techniques for CMOS Low Noise Amplifiers: A Tutorial

This tutorial catalogues and analyzes previously reported CMOS low noise amplifier (LNA) linearization techniques. These techniques comprise eight categories: a) feedback; b) harmonic termination; c) optimum biasing; d) feedforward; e) derivative superposition (DS); f) IM2 injection; g) noise/distortion cancellation; and h) post-distortion. This paper also addresses broadband-LNA-linearization issues for emerging reconfigurable multiband/multistandard and wideband transceivers. Furthermore, we highlight the impact of CMOS technology scaling on linearity and outline how to design a linear LNA in a deep submicrometer process. Finally, general design guidelines for high-linearity LNAs are provided.

Rapid Rotary Scanner and Portable Coherent Wideband Q-Band Transceiver for High-Resolution Millimeter-Wave Imaging Applications

Millimeter-wave imaging techniques, based on synthetic aperture focusing (SAF), have been successfully used for nondestructive testing (NDT) of various composite and aerospace structures. Most current imaging mechanisms utilize raster scanning platforms, whereby the imaging system is scanned in a rectangular grid over the structure-under-test (SUT). Most raster scanning platforms, although relatively simple in design and construction, are inherently slow. Furthermore, SAF techniques necessitates the use of vector-measuring instruments such as a vector network analyzer (VNA), which are typically: 1) bulky; 2) cannot be mounted on scanning platforms; 3) are not suitable for in-field use; and 4) expensive. These factors limit the effectiveness of these millimeter-wave imaging techniques in applications where frequent and rapid inspection of large structures is required. Hence, there is a great demand for rapid mechanical scanning systems combined with portable wideband transceivers in order to increase the utility of these imaging techniques, and provide a real solution to many practical NDT applications. To this end, a unique rotary scanner system, capable of scanning a relatively large area in a relatively short span of time, was designed and constructed. In addition, a custom-designed portable transceiver system operating in the frequency range of 35-45 GHz (Q-band) was developed and incorporated into the rotary scanner system for producing coherent (amplitude and phase) and accurate data suitable for synthetic aperture imaging and the 10-GHz bandwidth allows the generation of relatively high-resolution millimeter-wave holographical images. This paper presents the design of the rotary scanning system, the associated Q-band transceiver and the integration of the two systems via a custom-designed software. To illustrate the efficacy of the complete imaging system, SAF of several complex structures produced using the proposed system, are presented and discussed.

Largely reconfigurable impulse radio UWB transceiver

This letter presents a new and efficient digital baseband architecture for impulse radio ultra wideband (IR-UWB) transceivers with reconfigurable capacities for wireless sensor network (WSN) applications. An implementation is done on FPGA for validation by measurements. It achieves the highest data rate and the largest number of operating modes for an IR-UWB reconfigurable transceiver, to the best of the author's knowledge. Measurements demonstrate reconfigurability in data rate (from 4 to 125 MBits/s), chip duration (from 8 to 32 ns), pulse duration (from 1 to 4 ns), bit duration (from 8 to 256 ns), processing gain (from 1 to 8 pulses/bit), occupied bandwidth, radio range, BER performance, synchronization accuracy (from 0.5 to 4 ns), pulse amplitude, transmitted power density, duty cycle (from 3 to 50 %), power consumption, spectrum occupation, and maximum supported UWB channel delay spread (from 4 to 31 ns).

Toward a Highly Accurate Ambulatory System for Clinical Gait Analysis via UWB Radios

In this paper, we propose and investigate a low-cost and low-complexity wireless ambulatory human locomotion tracking system that provides a high ranging accuracy (intersensor distance) suitable for the assessment of clinical gait analysis using wearable ultra wideband (UWB) transceivers. The system design and transceiver performance are presented in additive-white-gaussian noise and realistic channels, using industry accepted channel models for body area networks. The proposed system is theoretically capable of providing a ranging accuracy of 0.11 cm error at distances equivalent to interarker distances, at an 18 dB SNR in realistic on-body UWB channels. Based on real measurements, it provides the target ranging accuracy at an SNR = 20 dB. The achievable accuracy is ten times better than the accuracy reported in the literature for the intermarker-distance measurement. This makes it suitable for use in clinical gait analysis, and for the characterization and assessment of unstable mobility diseases, such as Parkinson's disease.

A 55–64 GHz Fully-Integrated Sub-Harmonic Wideband Transceiver in 130 nm CMOS Process

In this letter, a 55-64 GHz compact fully-integrated gigabit transceiver with sub-harmonic pump technique is presented. The transceiver consists of a single-pole-double-throw (SPDT) traveling wave switch, a low-noise amplifier (LNA), a buffer amplifier (BA), and two sub-harmonic resistive mixers for up-conversion and down-conversion, respectively. The transceiver using 130 nm standard CMOS technology achieves an up-conversion gain of 7.4 dB at 62 GHz and down-conversion gain of 7.2 dB at 60 GHz with a compact chip size of 1.2 mm2. The 3 dB frequency bandwidth ranges from 55 to 64 GHz, which can cover the whole frequency band for 802.15.TG3C WPAN applications. For system applications, gigabit BPSK modulation signal test is successfully performed in this work.

On capacity-optimal precoding for multiple antenna systems subject to EIRP restrictions

Ultra wideband transceivers promise multi-gigabit per second performance at power consumptions commensurate with portable devices. Future products are likely to adopt multiple antennas to maximize performance. Severe FCC EIRP restrictions impose an interesting system design constraint. In this paper, capacity optimal multiple antenna transmission schemes are investigated for EIRP restricted systems under the assumption that the channel is known at the transmitter. It is shown that per subcarrier antenna power allocation, which reduces to antenna selection at low SNR or when using one receive antenna, is optimal for some transmitter configurations. The improvements in capacity are quantified for representative channels.

An Algorithm for Positioning Relays and Point Scatterers in Wireless Systems

In this letter, we discuss the problem of positioning an unknown number of amplify-and-forward relays or point scatterers using a wireless network of wideband transceivers. We propose to model this positioning problem as an assignment problem. In doing so, we avoid the problems associated with an exhaustive gridsearch approach, which has recently been proposed to solve the problem. Numerical simulations show promising results in terms of performance and robustness.

Ultra wide‐band bow‐tie slot antenna fed by a CPW‐to‐CPW transition loaded with inductively coupled slots

AbstractThis letter presents novel modified coplanar waveguide (CPW) bow‐tie slot printed antennas fed by a CPW‐to‐CPW transition. The proposed modules are miniature shaped, low‐profile radiators with bidirectional radiation characteristics, which can be optimally integrated in future ultra wide band transceivers. An innovative asymmetric bow‐tie configuration is introduced for the first time and the use of inductively coupled slots for bandwidth enhancement is additionally proposed and experimentally studied. The incorporated tapered CPW‐to‐CPW transition from Zin ≠ 50 Ω to Zin = 50 Ω offers upgraded impedance bandwidth and compatibility with 50 Ω CPW or coaxial lines. Details of the design procedure and experimental results exhibiting a bandwidth (VSWR &lt;2) of 123% are presented. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1816–1820, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21768

A 10-35-GHz six-channel microstrip multiplexer for wide-band communication systems

A six-channel multiplexer composed of parallel-coupled microstrip bandpass filters is developed. The passbands of the filters, i.e., channel frequencies, are 10, 12, 19, 21, 32, and 35 GHz. The operating frequency range of the multiplexer is so wide that a new method of harmonic suppression is devised for the filters designed at 10 and 12 GHz. The method is simple and does not require any change to the conventional parallel-coupled microstrip bandpass filter. A design procedure for the microstrip multiplexer is then introduced with a rule to set up initial conditions for better optimization. The designed multiplexer does not need any tuning elements, and the measurement results show insertion losses between 2.0-3.2 dB for all six channels. The multiplexer developed in this paper has been used in the wide-band transceiver system.