Low-power Ultra-wideband Research Articles

Design of Impedance Matching Network for Low-Power, Ultra-Wideband Applications

This paper addresses the design of ultra-wideband (UWB) impedance matching networks operating in the unlicensed 3.1–10.6 GHz frequency band for low-power applications. It improves the simplified real frequency technique (SRFT) by adding a realizability check and employing an iterative approach with different initial guesses in optimization to achieve realizable solutions under the requirements of UWB, low-power consumption, and a minimum number of circuit components. The comparison of solutions obtained using the SRFT with published solutions based on the Chebyshev filter theory is presented. It is shown that the optimal SRFT solution requires fewer components in the impedance matching network, maximizes the RF power delivery over the UWB spectrum with a reflection coefficient below −10 dB, and allows for circuit optimization to reduce power consumption. Using the improved SRFT, it demonstrates a systematic approach to find the strategies and limitations of designing the input matching networks for low-power UWB applications using GlobalFoundries 90 nm BiCMOS technology.

Experimental Evaluation of Sensor Fusion of Low-Cost UWB and IMU for Localization under Indoor Dynamic Testing Conditions.

Autonomous systems usually require accurate localization methods for them to navigate safely in indoor environments. Most localization methods are expensive and difficult to set up. In this work, we built a low-cost and portable indoor location tracking system by using Raspberry Pi 4 computer, ultra-wideband (UWB) sensors, and inertial measurement unit(s) (IMU). We also developed the data logging software and the Kalman filter (KF) sensor fusion algorithm to process the data from a low-power UWB transceiver (Decawave, model DWM1001) module and IMU device (Bosch, model BNO055). Autonomous systems move with different velocities and accelerations, which requires its localization performance to be evaluated under diverse motion conditions. We built a dynamic testing platform to generate not only the ground truth trajectory but also the ground truth acceleration and velocity. In this way, our tracking system's localization performance can be evaluated under dynamic testing conditions. The novel contributions in this work are a low-cost, low-power, tracking system hardware-software design, and an experimental setup to observe the tracking system's localization performance under different dynamic testing conditions. The testing platform has a 1 m translation length and 80 μm of bidirectional repeatability. The tracking system's localization performance was evaluated under dynamic conditions with eight different combinations of acceleration and velocity. The ground truth accelerations varied from 0.6 to 1.6 m/s2 and the ground truth velocities varied from 0.6 to 0.8 m/s. Our experimental results show that the location error can reach up to 50 cm under dynamic testing conditions when only relying on the UWB sensor, with the KF sensor fusion of UWB and IMU, the location error decreases to 13.7 cm.

A Miniaturized Ultra-Wideband Radar for UAV Remote Sensing Applications

This letter presents a novel approach to build a compact lightweight unmanned aerial vehicle (UAV) radar for remote sensing applications. The proposed radar exploits the recent advancement of an automotive radar chip for broadband chirp generation and rapid data processing. To compensate for the path losses and improve penetration at the millimeter-wave (mm-wave) frequency range, up- and down-converters are developed to generate an ultra-wideband (UWB) (3.25–5.15 GHz) chirp signal. The total payload of the radar is 2.5 kg. The proposed radar is installed on an UAV and tested in the field at a 100-m altitude above the ground surface. The results show that the compact low-power UWB radar can be used to map vegetation and soil moisture with fine resolution.

ULoc

A myriad of IoT applications, ranging from tracking assets in hospitals, logistics, and construction industries to indoor tracking in large indoor spaces, demand centimeter-accurate localization that is robust to blockages from hands, furniture, or other occlusions in the environment. With this need, in the recent past, Ultra Wide Band (UWB) based localization and tracking has become popular. Its popularity is driven by its proposed high bandwidth and protocol specifically designed for localization of specialized "tags". This high bandwidth of UWB provides a fine resolution of the time-of-travel of the signal that can be translated to the location of the tag with centimeter-grade accuracy in a controlled environment. Unfortunately, we find that high latency and high-power consumption of these time-of-travel methods are the major culprits which prevent such a system from deploying multiple tags in the environment. Thus, we developed ULoc, a scalable, low-power, and cm-accurate UWB localization and tracking system. In ULoc, we custom build a multi-antenna UWB anchor that enables azimuth and polar angle of arrival (henceforth shortened to '3D-AoA') measurements, with just the reception of a single packet from the tag. By combining multiple UWB anchors, ULoc can localize the tag in 3D space. The single-packet location estimation reduces the latency of the entire system by at least 3×, as compared with state of art multi-packet UWB localization protocols, making UWB based localization scalable. ULoc's design also reduces the power consumption per location estimate at the tag by 9×, as compared to state-of-art time-of-travel algorithms. We further develop a novel 3D-AoA based 3D localization that shows a stationary localization accuracy of 3.6 cm which is 1.8× better than the state-of-the-art two-way ranging (TWR) systems. We further developed a temporal tracking system that achieves a tracking accuracy of 10 cm in mobile conditions which is 4.3× better than the state-of-the-art TWR systems.

Robust ultra-wideband range error mitigation with deep learning at the edge

Ultra-wideband (UWB) is the state-of-the-art and most popular technology for wireless localization. Nevertheless, precise ranging and localization in non-line-of-sight (NLoS) conditions is still an open research topic. Indeed, multipath effects, reflections, refractions, and complexity of the indoor radio environment can easily introduce a positive bias in the ranging measurement, resulting in highly inaccurate and unsatisfactory position estimation. This article proposes an efficient representation learning methodology that exploits the latest advancement in deep learning and graph optimization techniques to achieve effective ranging error mitigation at the edge. Channel Impulse Response (CIR) signals are directly exploited to extract high semantic features to estimate corrections in either NLoS or LoS conditions. Extensive experimentation with different settings and configurations has proved the effectiveness of our methodology and demonstrated the feasibility of a robust and low computational power UWB range error mitigation.

A UHF/UWB Hybrid RFID Tag With a 51-m Energy-Harvesting Sensitivity for Remote Vital-Sign Monitoring.

A novel ultra-high frequency (UHF)/ultra-wideband (UWB) hybrid RFID tag is reported for object-specific remote vital-sign monitoring application. The tag achieves a record energy-harvesting sensitivity at UHF band by codesigning a meander dipole antenna and a passive rectifier. The especially high quality-factor makes the frontend sensitive to near-field motions such as heartbeats and respiration in a wearable setting. The custom CMOS IC of approximately 1-μW power consumption builds around a low-power UWB transmitter and converts variations of the supply voltage to the impulse repetition rate. The tag consisting of the IC and UHF/UWB antennas requires no other discrete components and features a size of 4.2 cm × 2.9 cm and a weight of 0.93 g. A long-distance experiment verifies that the tag can be wirelessly powered up at 51 meters from a 4-W equivalent-isotropic-radiation-power (EIRP) UHF transmitter. Remote vital-sign monitoring is validated on a human subject, in which the UHF power source is placed 2 meters away from the subject with a power emission of less than 20 dBm. This work proposes a first-of-its-kind remote vital-sign monitoring scheme based on a noncontact wearable tag. The design of the far-field energy-harvesting frontend with a record sensitivity serves as a reference for future works on battery-free remote sensors.

Enabling Optimization-Based Localization for IoT Devices

In this paper, we propose an embedded optimization approach for the localization of Internet of Things (IoT) devices making use of range measurements from ultra-wideband (UWB) signals. Low-cost, low-power UWB radios provide time-of-arrival measurements with decimeter accuracy over large distances. UWB-based localization methods have been envisioned to enable feedback control in IoT applications, particularly, in GPS-denied environments, and large wireless sensor networks. In this paper, we formulate the localization task as a nonlinear least-squares optimization problem based on two-way time-of-arrival measurements between the IoT device and several UWB radios installed in a 3-D environment. For the practical implementation of large-scale IoT deployments we further assume only approximate knowledge of the UWB radio locations. We solve the resulting optimization problem directly on IoT devices equipped with off-the-shelf microcontrollers using state-of-the-art code generation techniques for plug-and-play deployment of the nonlinear-programming algorithms. This paper further provides practical implementation details to improve the localization accuracy for feedback control in experimental IoT applications. The experimental results finally show that subdecimeter localization accuracy can be achieved using the proposed optimization-based approach, even when the majority of the UWB radio locations are unknown.

Negative lumped element matching technique for performance enhancement of ultra-wideband LNA

The paper aims at designing of two stage cascaded ultra-wideband (UWB) low noise amplifier (LNA) by using negative image amplifier technique. The objective of this article is to show the performance improvement using negative image amplifier technique and realization of negative valued lumped elements into microstrip line geometry. The innovative technique to realize the negative lumped elements are carried out by using Richard's Transformation and transmission line calculation. The AWR microwave office tool is used to obtain characteristics of UWB LNA design with hybrid microwave integrated circuit (HMIC) technology. The 2-stage cascaded LNA design using negative image amplifier technique achieves average gain of 23dB gain and low noise Figure of less than 2dB with return loss less than −8dB for UWB 3–10GHz. The Proper bias circuit is extracted using DC characteristics of transistor at biasing point 2V, 20mA and discussed in detail with LNA layout. The negative image matching technique is applied for both input and output matching network. This work will be useful for all low power UWB wireless receiver applications.

Design of Low Power UWB CMOS Low Noise Amplifier using Active Inductor for WLAN Receiver

This paper presents a low power Low Noise Amplifier (LNA) using 0.18µm CMOS technology for ultra wide band (UWB) applications. gm boosting common gate (CG) LNA is designed to improve the noise performance. For the reduction of on chip area, active inductor is employed at the input side of the designed LNA for input impedance matching. The proposed UWB LNA is designed using Advanced Design System (ADS) at UWB frequency of 3.1-10.6 GHz. Simulation results show that the gain of 10.74+ 0.01 dB, noise figure is 4.855 dB, input return loss <-13 dB and 12.5 mW power consumption.

A CMOS Ultrawideband Pulse Generator for 3–5 GHz Applications

A low-power ultrawideband (UWB) pulse generator based on pulsed oscillator architecture for 3-5 GHz applications is proposed. The pulsed oscillator is improved, so it realizes binary phase shift keying (BPSK) modulation. Unlike ON-OFF keying or pulse-position modulation (PPM), BPSK can scramble the spectrum, so it can be used in high pulse rate applications without having spectral line problem. The signal structure in this design is burst mode of PPM+BPSK. The proposed UWB pulse generator was successfully implemented on 0.18-μm CMOS technology. The peak-to-peak amplitude of output pulse is about 220 mV with 50-Ω load, the maximum power consumption is 4 mW at a raw data rate of 7.8 Mbps and the energy consumption is 32 pJ/pulse at a pulse rate of 125 Mpulses/s.

A Novel Complex-Coefficient In-Band Interference Suppression Algorithm for Cognitive Ultra-Wide Band Wireless Sensors Networks.

With the rapid development of wireless communication systems and electronic techniques, the limited frequency spectrum resources are shared with various wireless devices, leading to a crowded and challenging coexistence circumstance. Cognitive radio (CR) and ultra-wide band (UWB), as sophisticated wireless techniques, have been considered as significant solutions to solve the harmonious coexistence issues. UWB wireless sensors can share the spectrum with primary user (PU) systems without harmful interference. The in-band interference of UWB systems should be considered because such interference can severely affect the transmissions of UWB wireless systems. In order to solve the in-band interference issues for UWB wireless sensor networks (WSN), a novel in-band narrow band interferences (NBIs) elimination scheme is proposed in this paper. The proposed narrow band interferences suppression scheme is based on a novel complex-coefficient adaptive notch filter unit with a single constrained zero-pole pair. Moreover, in order to reduce the computation complexity of the proposed scheme, an adaptive complex-coefficient iterative method based on two-order Taylor series is designed. To cope with multiple narrow band interferences, a linear cascaded high order adaptive filter and a cyclic cascaded high order matrix adaptive filter (CCHOMAF) interference suppression algorithm based on the basic adaptive notch filter unit are also presented. The theoretical analysis and numerical simulation results indicate that the proposed CCHOMAF algorithm can achieve better performance in terms of average bit error rate for UWB WSNs. The proposed in-band NBIs elimination scheme can significantly improve the reception performance of low-cost and low-power UWB wireless systems.

A short-impulse UWB BPSK transmitter for large-scale neural recording implants.

In this paper, a short-impulse ultra-wide band (UWB) transmitter is introduced to enable large-scale neural recordings within miniature brain implants including thousands of channels. The proposed impulse radio UWB transmitter uses a BPSK modulation scheme, the carrier signal of which uses only two delayed impulses to encode the transmitted signal. The proposed UWB transmitter has been implemented into a CMOS 180 nm technology. It occupies 300 μm × 230 μm, and consumes only 6.7 pJ/bit from a 1.8-V supply. Experimental results show that the transmitter has a bandwidth of 2.6 GHz to 5.6 GHz and achieves a maximum data rate of 800 Mbps, which outperforms existing low-power UWB transmitters for similar applications.

Permutation-Based Noncoherent Space-Time Codes With Analog Energy Detection for IR-UWB Communications With PPM

In this paper, we consider the problem of space-time (ST) coding for the noncoherent ultra-wideband (UWB) systems with pulse position modulation (PPM). In particular, we propose the first known family of ST codes that lends itself to optimal decoding with the energy detectors. Energy detection avoids the sampling of the received signal where the sampling rates can be prohibitively high and escapes from the challenging task of estimating the dense multi-path UWB channel. In the absence of design criteria that are adapted to the problem under consideration, we derive two novel design criteria and propose the novel construction accordingly. The proposed code is based solely on permutations, and hence it does not introduce any constellation expansion on the totally-real and unipolar PPM signal set. In other words, the components of the constructed codewords are limited to either zero or one indicating the absence or presence of an UWB pulse in the corresponding PPM slot, respectively. The above characteristics result in a remarked simplicity of the ST encoder/decoder making it an appealing solution to low-cost and low-power UWB systems. For a system equipped with $n$ transmit antennas, we prove that the proposed code is capable of achieving a full transmit diversity order with $M$ -PPM constellations for $M>n+1$ while transmitting at the rate of $({1}/{n})\log _{2}\binom {M-1}{n}$ bits per channel use.

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.

A linear high-gain and low-power CMOS UWB mixer

This article presents the design process, and analysis of a high-linearity, high-gain, low-power and inductorless 3.1–4.8 GHz ultra-wideband (UWB) down conversion mixer in a 0.18 μm CMOS process with a 1.8 supply voltage. In the proposed structure, the linearity of the conventional Gilbert cell mixer is increased about 10 dBm without losing the conversion gain using the modified derivative superposition and current-bleeding techniques. Moreover, power consumption of the conventional mixer is significantly decreased. Besides, the conversion gain and S11 of the mixer are hand calculated and the validity of the analytical formulas is verified by simulation results.

A 3–5 GHz low-power high-speed radiated power tuning UWB transmitter

To satisfy the different radiated power requirements for the ultra-wideband (UWB) data transmitting in the implantable electronic devices or the wireless component interconnections, a novel low-power high-speed UWB transmitter with radiated power tuning was proposed. The tunable radiated power is achieved by a UWB RF buffer with a peak value controller. The designed low-complex narrow pulse generator and digital ring on–off VCO ensure a high speed transmitting. The low power is realized by using a subtractor to eliminate the base-band component from the output of the VCO and making the UWB RF buffer and the VCO operating in standby mode. The design was fabricated by a standard 0.18μm CMOS technology. The test results show that the design can achieve maximum data-rate of 250Mbps, frequency bandwidth from 3 to 5GHz, radiated power tuning from −40dBm to −60dBm, low-power of 8pJ/bit, and small circuit area of 0.18mm2.

BER PERFORMANCE AND DATA THROUGHPUT OF SINUSOIDAL TEMPLATE- BASED IMPULSE-RADIO ULTRA WIDEBAND RECEIVERS FOR WIRELESS BODY AREA NETWORKS

Windowed sinusoidal template-based correlator receivers are good candidates for high-data rate low-pow er Ultra Wideband (UWB) systems. Their performance approaches the performance of optimal detectors and provides low-power consumption. However, the ultra short pulses of UWB technology makes it sensitive t o timing-errors. In this paper, the Bit-Error-Rate (B ER) performance and maximum allowable data throughput of Equally-Correlated Pulse Position Modulation (EC-PPM) modulation scheme in the presence of timing-jitter are studied and compared for low-p ower sinusoidal template based correlator receivers . Additive White Gaussian Noise (AWGN), Nakagami-m fading, industrially accepted on-body IEEE 802.15.6a and actual on-body channels are considere d. Numerical results show that the maximum SNR penalty when using sinusoidal templates is ≈2 dB for the same BER and the corresponding data-throughput degradation is 5 Mbps.

A low power and high linearity UWB low noise amplifier (LNA) for 3.1–10.6 GHz wireless applications in 0.13 μm CMOS process

In this paper, a low power ultra-wideband (UWB) CMOS LNA was designed exploiting source inductive degeneration technique operating in the frequency range of 3.1–10.6GHz. In order to achieve low noise figure and high linearity simultaneously, a modified three-stage UWB LNA with inter-stage inductors was proposed. Forward Body-Biased (FBB) technique was used to reduce threshold voltage and power consumption at the first and third stages. The second stage is a push–pull topology exploiting the complementary characteristics of NMOS and PMOS transistors to enhance the linearity performance. The proposed LNA was simulated in standard 0.13μm CMOS process. A gain of 19.5±1.5dB within the entire band was exhibited. The simulated noise figure (NF) was 1–3.9dB within the bandwidth. A maximum simulated third-order input intercept point (IIP3) of 4.56dBm while consuming 4.1mW from a 0.6 power supply was achieved. The simulated input return loss (S11) was less than −5dB from 4.9 to 12.1GHz. The output return loss (S22) was below −10.6dB and S12 was better than −70.6dB.

A novel low power UWB cascode SiGe BiCMOS LNA with current reuse and zero-pole cancellation

A low power cascode SiGe BiCMOS low noise amplifier (LNA) with current reuse and zero-pole cancellation is presented for ultra-wideband (UWB) application. The LNA is composed of cascode input stage and common emitter (CE) output stage with dual loop feedbacks. The novel cascode-CE current reuse topology replaces the traditional two stages topology so as to obtain low power consumption. The emitter degenerative inductor in input stage is adopted to achieve good input impedance matching and noise performance. The two poles are introduced by the emitter inductor, which will degrade the gain performance, are cancelled by the dual loop feedbacks of the resistance-inductor (RL) shunt–shunt feedback and resistance-capacitor (RC) series–series feedback in the output stage. Meanwhile, output impedance matching is also achieved. Based on TSMC 0.35μm SiGe BiCMOS process, the topology and chip layout of the proposed LNA are designed and post-simulated. The LNA achieves the noise figure of 2.3–4.1dB, gain of 18.9–20.2dB, gain flatness of ±0.65dB, input third order intercept point (IIP3) of −7dBm at 6GHz, exhibits less than 16ps of group delay variation, good input and output impedances matching, and unconditionally stable over the whole band. The power consumption is only 18mW.

A Low-Voltage, Low-Power, and Low-Noise UWB Mixer Using Bulk-Injection and Switched Biasing Techniques

This paper presents a low-voltage, low-power, low-noise, and ultra-wideband (UWB) mixer using bulk-injection and switched biasing techniques. The bulk-injection technique is implemented for a low supply voltage, thus resulting in low power consumption. This technique also allows for a flat conversion gain over a wide range of frequencies covering the full UWB band; this is a result of the integration of the RF transconductance stage and the local oscillator switching stage into a single transistor that is able to eliminate parasitic effects. Moreover, since the bulk-injection transistors of the mixer are designed to operate in the subthreshold region, current dissipation is reduced. A switched biasing technique for the tail current source, in place of static biasing, is adopted to reduce noise. The effects of modulated input signals, such as AM and FM, are simulated and measured to demonstrate the robustness of the switched biasing technique. The proposed mixer offers a measured conversion gain from 7.6 to 9.9 dB, a noise figure from 11.7 to 13.9 dB, and input third-order intercept point from - 10 to - 15.5 dBm, over 2.4 to 11.9 GHz, while consuming only 0.88 mW from a 0.8-V supply voltage. The chip size including the test pads is 0.62×0.58 mm2 using a 0.18-μm RF CMOS process.