Wireless Communication Circuits Research Articles

Gold Nanowire Sponge Electrochemistry for Permeable Wearable Sweat Analysis Comfortably and Wirelessly.

Electrochemistry-based wearable and wireless sweat analysis is emerging as a promising noninvasive method for real-time health monitoring by tracking chemical and biological markers without the need for invasive blood sampling. It offers the potential to remotely monitor human sweat conditions in relation to metabolic health, stress, and electrolyte balance, which have implications for athletes, patients with chronic conditions, and individuals for the early detection and management of health issues. The state-of-the-art mainstream technology is dominated by the concept of a wearable microfluidic chip, typically based on elastomeric PDMS. While outstanding sensing performance can be realized, the design suffers from the poor permeability of PDMS, which could cause skin redness or irritation. Here, we introduce an omnidirectionally permeable, deformable, and wearable sweat analysis system based on gold nanowire sponges. We demonstrate the concept of all-in-one soft sponge electrochemistry, where the working, reference, and counter electrodes and electrolytes are all integrated within the sponge matrix. The intrinsic porosity of sponge in conjunction with vertically aligned gold nanowire electrodes gives rise to a high electrochemically active surface area of ∼67 cm2. Remarkably, this all-in-one sponge-based electrochemical system exhibited stable performance under a pressure of 10 kPa and 300% omnidirectional strain. The gold sponge biosensing electrodes could be sandwiched between two biocompatible sweat pads, which can serve as natural sweat collection and outflow layers. This naturally biocompatible and permeable platform can be integrated with wireless communication circuits, leading to a wireless sweat analysis system for the real-time monitoring of glucose, lactate, and pH during exercise.

Frequency doubler utilizing hetero gate dielectric tunnel field-effect transistor

With the rapid advancements in wireless communication and high-density integrated circuits, the demand for high-frequency sources has become paramount for transmitting vast amounts of information. Modern communication systems often utilize low-frequency sources at the transmitting end, converting them into high-frequency carriers through Intermediate Frequency (IF) for transmission to the receiving end. However, challenges arise in stabilizing high-frequency Voltage Controlled Oscillators (VCOs), leading to the necessity of Frequency Multipliers (FMs) in high-frequency circuits. While existing FMs face issues like harmonic distortion due to internal nonlinear devices, this paper proposes a single-device Frequency Doubler (FD) operation using Hetero-Gate Tunnel Field Effect Transistor (HG-TFET) with ambipolar characteristics. HG-TFET integrates high-κ (HK) materials and an HG structure in the gate dielectric, achieving independent control of tunneling distances and synchronous operation of source-to-channel and channel-to-drain tunneling currents (I SC and I CD) to facilitate FD operation. The paper presents the HG-TFET structure, process flow, and simulation models, followed by an exploration of its operating mechanism and characteristics. The FD circuit configuration, operational principles, and conditions for normal operation are detailed, emphasizing the importance of aligning I SC and I CD. The impact of adjusting HK lengths on I SC and I CD is analyzed, demonstrating the ability to independently control these currents through HG-TFET. Simulation results for FD operation under varying HK lengths (1–10 nm) validate the proposed approach. Additionally, the paper investigates the influence of dielectric constant (10–32) and gate dielectric thickness (2–5 nm) on FD performance, highlighting the potential for further optimization. In conclusion, this study establishes a foundation for normal FD operation through the symmetrical control of ambipolar and on currents using HG-TFET. The proposed structure and techniques open avenues for improving the efficiency and reliability of frequency-doubling applications in high-frequency circuits.

A Single-Switch WPT Circuit With Inherent CCO–CVO for Battery Charging

In order to obtain a highly reliable and low-cost wireless charging method. This paper proposes a single-switch wireless power transfer (WPT) circuit with inherent constant current output (CCO) and constant voltage output (CVO) for battery charging. Compared with a full bridge WPT circuit, the structure and control strategy of the proposed circuit is simple. And the shoot-through problem could be avoided in the proposed circuit. In order to realize the inherent CCO-CVO without the wireless communication and extra control circuit, the double-D quadrature (DDQ) coils are used in this paper to remove cross-coupling between coils. And the corresponding compensation network is designed to realize the automatic transition from the CCO to CVO. There are no active control schemes used in the proposed method. The compensation design could enable primary-side protection of over-current against the accidental removal of the secondary side. There is no compensation inductor in the secondary circuit, which reduces the volume and weight of the secondary circuit. Moreover, the transfer gain does not rely on the transformer parameters, and more parameters design freedom can be realized. Finally, the simulation and the experimental verification are carried out to verify the superiority of the proposed circuit.

Advancing Robotic Gripper Control with the Integration of Flexible Printed Pressure Sensors

A pressure sensor array fabricated on a flexible substrate using the printing method can be easily mounted in various locations by combining it with a wireless communication circuit. This is particularly advantageous for applications where wiring is difficult, such as the tip of a robot gripper. Additionally, printed devices are highly efficient in material utilization, facilitating large areas and low‐cost production. In recent years, there has been growing interest in the harmonious interaction between robots and humans, and the intelligentization of robots is a worthwhile research area. Herein, a method for realizing intelligent gripping force control and object recognition robots using a printed flexible pressure sensor array in combination with a wireless communication circuit is proposed. By mounting the sensor array on a robot gripper and performing arithmetic processing on software, these capabilities are achieved.

Design of a two-stage Dickson RF-DC Rectifier for 2.45 GHz wireless energy harvesting

Wireless electromagnetic charging has established itself as a module of great relevance in the context of Internet of Things devices. Most commercial applications use wireless radio frequency charging in the 2.45GHz band. In this study, a compact RF-DC rectifier operating at 2.45 GHz is analyzed for an input power range of 0 to 8 dBm and with HSMS 2862 Schottky diodes that are designed and simulated in this article. Impedance matching is simply constructed using a radial stub circuit. To significantly increase the output DC voltage, the rectifier is constructed using the Dickson multi-stage voltage doubler configuration. The performance of the rectifier is evaluated through simulation for an operating frequency of 2.45 GHz, the efficiency parameter reaches 38.8% after electromagnetic co-simulation for an input power of 8 dBm. This rectifier topology is found in several applications in wireless communication and electronic circuits.

Floquet engineering-based frequency demodulation method for wireless THz short-range communications

This study introduces a novel theoretical framework for detecting and decoding wireless communication signals in the nanoscale range operating at terahertz (THz) frequencies. Initially, we investigate the Floquet states in a dressed 2D semiconductor quantum well and derive an analytical expression to determine its longitudinal conductivity. The results indicate that the longitudinal conductivity of a dressed 2D semiconductor can be tailored to specific requirements by manipulating the frequency of the external dressing field. Furthermore, carefully selecting the intensity and polarization type of the external dressing field enables fine-tuning and optimization of the conductivity. To evaluate the effectiveness of each dressing field configuration, we present a figure of Merit (FoM) assessment that determines the maximum possible change in conductivity within the considered frequency range. The proposed theory introduces a mechanism capable of identifying frequency-modulated communication signals in the THz range and performing frequency demodulation. We comprehensively analyze of the demodulator’s transfer function in the receiver. Consequently, we establish that the transfer function exhibits linear behavior over a specific frequency range, rendering it suitable for frequency demodulation. Finally, we provide a numerical illustration of a frequency demodulation scenario. The breakthrough uncovered in this study opens up possibilities for the development of high-efficiency, lightweight, and cutting-edge chip-scale wireless communication devices, circuits, and components.

Integrated Circuits for Wireless Communications: Research Activities at the University of California, San Diego: Circuits Research for Wireless Communications at the University of California, San Diego

The continuing demand for improved wireless connectivity and enhanced data rates has spurred worldwide research in microwave and millimeter (mm)-wave circuits and systems within academia, government, and industrial centers. At the University of California, San Diego (UCSD), the Center for Wireless Communications (CWC) was established more than two decades ago and has contributed to analog, microwave, and millimeter circuits and systems research; communication and information theory; coding; and application studies for 4G, 5G, and 6G wireless systems. This article highlights recent UCSD research efforts, emphasizing the microwave and mm-wave circuits and systems and accompanying analog circuit techniques, carried out in conjunction with the CWC.

Guest Editorial

This Transactions on Microwave Theory and Techniques&’ Mini-Special Issue includes eight papers from the 2022 IEEE Radio and Wireless Week (RWW 2022) held in Las Vegas, NV, USA, January 16–19, 2022. The Radio and Wireless Week consists of five related conferences that focus on the intersection between wireless communication theory, systems, circuits, and device technologies: the Radio and Wireless Symposium (RWS), the Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR), the Topical Meetings on Silicon Monolithic Integrated Circuits in RF Systems (SiRF), the Topical Conference on Wireless Sensors and Sensor Networks (WiSNet), and the Space Hardware and Radio Conference (SHaRC). Radio and Wireless Week is thus a multidisciplinary event bringing together innovations that are happening across the broad wireless spectrum. A total of 185 papers were submitted to the RWW 2022 Technical Program Committee, of which 135 papers were accepted for presentation and publication online on the IEEE Xplore website. Together with the technical sessions, RWW 2022 successfully held seven workshops, a special focus session on massive MIMO beamforming technologies for 5G and beyond, a plenary presentation on topics related to artificial intelligence in circuit design and 6G, a dedicated track for the IEEE Distinguished Microwave Lecturers, and a demo track session to show the latest innovative wireless experimental achievements. For the second time, RWW had a live session on Distinguished Women in Microwaves bringing together a panel of women who have contributed to the microwave society for the last few years including high-quality talks in radio and wireless applications.

Wireless Non-Invasive Monitoring of Cholesterol Using a Smart Contact Lens.

Herein, a wireless and soft smart contact lens that enables real‐time quantitative recording of cholesterol in tear fluids for the monitoring of patients with hyperlipidemia using a smartphone is reported. This contact lens incorporates an electrochemical biosensor for the continuous detection of cholesterol concentrations, stretchable antenna, and integrated circuits for wireless communication, which makes a smartphone the only device required to operate this lens remotely without obstructing the wearer's vision. The hyperlipidemia rabbit model is utilized to confirm the correlation between cholesterol levels in tear fluid and blood and to confirm the feasibility of this smart contact lens for diagnostic application of cholesterol‐related diseases. Further in vivo tests with human subjects demonstrated its good biocompatibility, wearability, and reliability as a non‐invasive healthcare device.

A novel multi-resonant and wideband fractal antenna for telecommunication applications

<span>This letter presents the design, simulation, and measurement of a novel multiband fractal circular antenna for wireless applications. In the antenna design, we used a circular antenna where we took a ring. Then, in the first iteration, we added a new ring divided into two of the same size. For the second iteration, we added a ring of the same size after dividing it into two halves. In the third iteration, we added the third ring of the same size after dividing it into four. Due to the resonator defection, we were able to reduce the size of the starting antenna from 60×70×2 mm<sup>3</sup> to 50×50×1.6 mm<sup>3</sup>, to get the frequency of 2.48 GHz, and we generated new bandwidths with a high gain that reaches 5.02 dB. The proposed antenna radiation characteristics, such as the impedance matching, the gain, the radiation pattern, and the surface current distribution are presented and discussed. We find that the simulated and measured results are in acceptable agreement and affirm the good performance of the proposed antenna. The results obtained affirm that the proposed fractal antenna is a better candidate for integration into wireless communication circuits.</span>

Design, Implementation, and Deployment of Modular Battery Management System for IIoT-Based Applications

This paper proposes design and implementation of a battery management system (BMS) for the industrial internet of things (IIoT) enabled applications. The hardware and software development of this BMS is briefly presented in this paper. In terms of hardware development, the presented BMS have modular topology and has 1) high fault tolerance and 2) has exceptionally flexible deployment owing to its topology having multiple local management units (LMUs) connected to a central management unit (CMU). This hardware design approach aims to address the overall design efficiency and cost trade-off of BMS deployment. The hardware design efficiency is tested using actual deployment. In terms of fault tolerance using 1 – 3 LMUs at fault, the voltage monitoring accuracy is maintained for each LMUs. An average of 0.00017 V, 0.0008 V and 0.001 V voltage difference is yielded for 1, 2, and 3 modules at fault respectively. Additionally, core BMS sub-circuit is tested to verify hardware design efficiency such as the DC-to-DC converter which yielded 92.74%. Furthermore, the CMU is integrated with a wireless communication circuit that enables IIoT-based applications such as the emerging edge-based, and a plethora of intelligent deployment. In terms of software, the presented BMS aims to realize state-of-the-art processing through IIoT based approach. For software testing and verification, the BMS is deployed to an unmanned ground vehicle (UGV). The signal stability is tested for UGV based application at a 3500s deployment time whereas an average of 0.0010V voltage difference is yielded. This is verified using time markers which is further analyzed using software-based signal processing and acquisition simulation. Concisely, the proposed BMS aims to converge IIoT applications to its actual deployment. The proposed BMS is designed, implemented, and successfully deployed to test its viability both in the simulation platform and actual deployment.

Stretchy diodes deliver wireless communication

Over the past decade, researchers have made many skin-like medical and environmental sensors. But adding stretchable wireless communication circuits to these sensors has been difficult. Those radio frequency (RF) circuits rely on diodes, semiconductor devices that help convert AC power to DC power, working at megahertz frequencies. Researchers have now made the first stretchable high-frequency RF diode ( Nature 2021, DOI: 10.1038/s41586-021-04053-6). It could enable conformable sensors and radio frequency identification (RFID) tags—small electronic labels used to track objects—that can wirelessly receive or send signals. Zhenan Bao , the Stanford University chemical engineer who led the new work, has made other stretchable devices, but stretchy diodes proved to be both a materials and an engineering challenge, she says. Diodes contain a semiconductor sandwiched between electrodes and current collectors. “Electrodes and semiconductors that can pass a high current and also tolerate high mechanical deformation didn’t exist, so we had to invent

Integrating Sensing and Communications for Ubiquitous IoT: Applications, Trends, and Challenges

Recent advances in wireless communication and solid-state circuits together with the enormous demands of sensing ability have given rise to a new enabling technology, integrated (radar) sensing and communication (ISAC). ISAC captures two main advantages over dedicated sensing and communication functionalities: integration gain to efficiently utilize congested wireless/hardware resources, and even more interesting, coordination gain to balance dual-functional performance or/and perform mutual assistance. Triggered by ISAC, we are also witnessing a paradigm shift in the ubiquitous IoT architecture, in which the sensing and communication layers are tending to partially converge into a new layer, namely, the signaling layer. In this article, we first attempt to introduce a definition of ISAC, analyze the various influencing forces, and present several novel use cases. Then we complement the understanding of the signaling layer by presenting several key benefits in the IoT era. We classify existing dominant ISAC solutions based on the layers in which integration is applied. Finally, several challenges and opportunities are identified. We hope that this overview article will serve as a primary starting point for new researchers and offer a bird's-eye view of the existing ISAC-related advances.

A portable triboelectric spirometer for wireless pulmonary function monitoring

Coronavirus disease 2019 (COVID-19) as a severe acute respiratory syndrome infection has spread rapidly across the world since its emergence in 2019 and drastically altered our way of life. Patients who have recovered from COVID-19 may still face persisting respiratory damage from the virus, necessitating long-term supervision after discharge to closely assess pulmonary function during rehabilitation. Therefore, developing portable spirometers for pulmonary function tests is of great significance for convenient home-based monitoring during recovery. Here, we propose a wireless, portable pulmonary function monitor for rehabilitation care after COVID-19. It is composed of a breath-to-electrical (BTE) sensor, a signal processing circuit, and a Bluetooth communication unit. The BTE sensor, with a compact size and light weight of 2.5 cm3 and 1.8 g respectively, is capable of converting respiratory biomechanical motions into considerable electrical signals. The output signal stability is greater than 93% under 35%–81% humidity, which allows for ideal expiration airflow sensing. Through a wireless communication circuit system, the signals can be received by a mobile terminal and processed into important physiological parameters, such as forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC). The FEV1/FVC ratio is then calculated to further evaluate pulmonary function of testers. Through these measurement methods, the acquired pulmonary function parameters are shown to exhibit high accuracy (>97%) in comparison to a commercial spirometer. The practical design of the self-powered flow spirometer presents a low-cost and convenient method for pulmonary function monitoring during rehabilitation from COVID-19.

Application and Simulation of Fourier Analysis in Communication Circuit

This article mainly studies the application of Fourier analysis theory in wireless communication circuits. Firstly, the relevant basic theories of Fourier analysis are introduced, including the decomposition of periodic signal, the modulation characteristic of Fourier transform, and the system function; then the relevant applications of Fourier theory in communication circuits are introduced, such as high-frequency resonant power amplifier, amplitude modulation, demodulation and mixing, low-pass filter. Finally, the application of Fourier theory in communication circuits is simulated and analyzed through Multisim circuit simulation software.

Research on Wireless Water Quality Monitoring Method Based on STM32

Since the 21st century, people’s production and life have caused water pollution to varying degrees, so real-time monitoring of water quality has become crucial. Based on STM32, this paper proposes a water quality monitoring method that can continuously monitor three water quality parameters: water temperature, PH value, and turbidity. The water quality monitoring method is mainly based on the extended circuit of the STM32 series single-chip microcomputer, including PH sensor control circuit module, temperature sensor circuit module, wireless network communication circuit module, turbidity sensor circuit module, etc. Then based on the C language to write the MCU data acquisition program and the PC program developed on the virtual instrument design language platform, the PC program is mainly composed of the main PC and the MCU communication, data analysis and processing, process monitoring and other subroutines. The water quality monitoring method proposed in this paper can detect different water quality in real time through wireless transmission. This new method is not only suitable for the future development of the current water quality monitoring market, but also has a very promising application prospect.

Differential microstrip patch rectenna featuring consistent high gain over a wide operating bandwidth

AbstractThis paper presents three configurations of broadband differentially fed microstrip antenna for GSM1800, 1900 and 2100 MHz. The antennas are designed and fabricated using two different substrates for bottom and upper layer. The three antennas designed and tested have gain of 9.88, 9.66, and 11.14 dBi, respectively, at the center frequency. The proposed antennas also find its implementation in areas where, differential inputs/outputs wireless communication circuits are needed. Later, a differentially driven RF power harvesting system with maximum efficiency of 71%, 67% and 78% for a load of 520 Ω is also designed and developed.

Special issue on SoC and AI processors

Special issue on SoC and AI processors

Smart, soft contact lens for wireless immunosensing of cortisol.

Despite various approaches to immunoassay and chromatography for monitoring cortisol concentrations, conventional methods require bulky external equipment, which limits their use as mobile health care systems. Here, we describe a human pilot trial of a soft, smart contact lens for real-time detection of the cortisol concentration in tears using a smartphone. A cortisol sensor formed using a graphene field-effect transistor can measure cortisol concentration with a detection limit of 10 pg/ml, which is low enough to detect the cortisol concentration in human tears. In addition, this soft contact lens only requires the integration of this cortisol sensor with transparent antennas and wireless communication circuits to make a smartphone the only device needed to operate the lens remotely without obstructing the wearer's view. Furthermore, in vivo tests using live rabbits and the human pilot experiment confirmed the good biocompatibility and reliability of this lens as a noninvasive, mobile health care solution.

An integrated low-power Binary-PAM based wireless telemetry circuit for implantable cardiac pacemakers

A low-power wireless telemetry circuit integrated in an analog front-end (AFE) chip for implantable cardiac pacemakers is presented in this paper. With an on-chip telemetry circuit, the electrocardiogram (ECG) data can be transmitted directly from the AFE chip to a programmer outside the human body. Such a direct-memory-access (DMA) scheme improves data transmission efficiency and saves the overall power consumption. The proposed telemetry system employs a near-field inductive-coupling link with oscillating frequency of 128 ​kHz and a binary pulse-amplitude-modulation (PAM) strategy to achieve higher reliability. It consumes lower power and reach a longer communication distance when compared to conventional on-off-keying (OOK) modulation method. In order to further reduce the power consumption, pulse width adjustment technique is adopted in the transmitter. Also, edge detection and window detection techniques are employed in the receiver, making it more robust and immune to noise, disturbance and clock skew. The AFE chip is implemented using a 0.35-μm CMOS technology and the telemetry circuit occupies an active area of 1150umX350 ​μm. Measurement results show that the proposed wireless communication circuit can operate under a power supply range of 2.0–2.8 ​V, and achieves a maximum communication distance of 12 ​cm with current consumption lower than 26 ​μA and bit error rate less than 10−5.