LCMV beamforming for an L-band antenna array using the Xilinx RFSoC is presented. Implementation of the fully digital beamformer is discussed, including details of the implementation in hardware, High Level Synthesis (HLS), and software. The beamformer is demonstrated for several LCMV cases using an L-band array with eight elements.
Negative-U Defect Passivation in Oxide-Semiconductor by Channel Defect Self-Compensation Effect to achieve Low Bias Stress VTH Instability of Low-Thermal Budget IGZO TFT and FeFETs December 13, 2023
Publication
Negative-U Defect Passivation in Oxide-Semiconductor by Channel Defect Self-Compensation Effect to achieve Low Bias Stress VTH Instability of Low-Thermal Budget IGZO TFT and FeFETs
In this work, we elucidate the fundamental bias stress reliability mechanism in oxide-semiconductor devices and provided guidelines to improve interface/bulk-induced V TH degradation. We provide further insights into the defect-self compensation effect for the bilayer ITO-IGZO channel. Specifically, how our process approach led to effective passivation of channel defects such as negative-U defects, and ionized-oxygen-vacancy defects. With bilayer ITO-IGZO, we demonstrated 10x negative/positive bias stress (NBS/PBS), and 4x negative bias illumination stress (NBIS) improvement against the conventional mono-IGZO devices. Furthermore, under a low-thermal budget constraint, we implemented a sacrificial replacement gate stress memorization technique to enhance the ferroelectric phase to enable a double-gated (DG) IGZO FeFET. Our reliability-optimized DG ITO-IGZO FeFETs exhibit an enhanced memory window (MW) of 1.7V, excellent memory-write endurance of 10 7 cycles, outstanding memory retention with high I ON /I OFF of 10 6 after 10 4 s, record-low NBS/PNS V TH shift of 30mV, and NBIS V TH shift of 110mV after stress time of 1000s. These devices set a new oxide thin-film transistor (TFT) reliability record making major strides toward highly reliable BEOL logic and memory switches.
Researcher/Author:
Chun-Kuei Chen, Zefeng Xu, Sonu Hooda, Jieming Pan, Evgeny Zamburg, and Aaron Voon-Yew Thean
Hydrogels are ideal interfacing materials for on-skin healthcare devices, yet their susceptibility to dehydration hinders their practical use. While incorporating hygroscopic metal salts can prevent dehydration and maintain ionic conductivity, concerns arise regarding metal toxicity due to the passage of small ions through the skin barrier. Herein, an antidehydration hydrogel enabled by the incorporation of zwitterionic oligomers into its network is reported. This hydrogel exhibits exceptional water retention properties, maintaining ≈88% of its weight at 40% relative humidity, 25 °C for 50 days and about 84% after being heated at 50 °C for 3 h. Crucially, the molecular weight design of the embedded oligomers prevents their penetration into the epidermis, as evidenced by experimental and molecular simulation results. The hydrogel allows stable signal acquisition in electrophysiological monitoring of humans and plants under low-humidity conditions. This research provides a promising strategy for the development of epidermis-safe and biocompatible antidehydration hydrogel interfaces for on-skin devices.
Researcher/Author:
Ke He, Pingqiang Cai, Shaobo Ji, Zihan Tang, Zhou Fang, Wenlong Li, Jing Yu, Jiangtao Su, Yifei Luo, Feilong Zhang, Ting Wang, Ming Wang, Changjin Wan, Liang Pan, Baohua Ji, Dechang Li, and Xiaodong Chen
Efforts to design devices emulating complex cognitive abilities and response processes of biological systems have long been a coveted goal. Recent advancements in flexible electronics, mirroring human tissue’s mechanical properties, hold significant promise. Artificial neuron devices, hinging on flexible artificial synapses, bioinspired sensors, and actuators, are meticulously engineered to mimic the biological systems. However, this field is in its infancy, requiring substantial groundwork to achieve autonomous systems with intelligent feedback, adaptability, and tangible problem-solving capabilities. This review provides a comprehensive overview of recent advancements in artificial neuron devices. It starts with fundamental principles of artificial synaptic devices and explores artificial sensory systems, integrating artificial synapses and bioinspired sensors to replicate all five human senses. A systematic presentation of artificial nervous systems follows, designed to emulate fundamental human nervous system functions. The review also discusses potential applications and outlines existing challenges, offering insights into future prospects. We aim for this review to illuminate the burgeoning field of artificial neuron devices, inspiring further innovation in this captivating area of research.
Researcher/Author:
Ke He, Cong Wang, Yongli He, Jiangtao Su & Xiaodong Chen
Published in:
Chemical Reviews 2023, 123, 23, 13796-13865 (Review)
To download the paper, please proceed to:
10.1021/acs.chemrev.3c00527
A Resistor/Trimming-Less Self-Biased Current Reference Class with Area Down to $3,500um2, 42.8 pW Power and 10.4% Accuracy across Corner Wafers in 180 nm November 5, 2023
Publication
A Resistor/Trimming-Less Self-Biased Current Reference Class with Area Down to $3,500um2, 42.8 pW Power and 10.4% Accuracy across Corner Wafers in 180 nm
Current references are fundamental building blocks in sensor interfaces and other analog circuitries [1]–[9]. In applications with low-cost targets, their area and testing effort need to be minimized, and trimming must be eliminated. In power-constrained systems, their net power (i.e., not going into their output bias current IREF) and minimum supply voltage Vmin need to be kept low, so as to minimize the power burden and remove supply scaling limitations at the system level. Unfortunately, lower net power generally leads to poorer accuracy due to PVT variations, requiring innovation to make the power-accuracy tradeoff more favorable while avoiding trimming.
An L-band antenna array with eight elements and full digital beamforming using the Xilinx RFSoC is presented. Details of the implementation in the hardware, high level synthesis, and the software are provided. Digital beamforming is at the element level without the need for phase shifters or true time delays.
Researcher/Author:
Peizhuo Yang, Gong Chen & Koen Mouthaan
Published in:
Conference: 2023 IEEE International Symposium On Antennas And Propagation (ISAP)
To download the paper, please proceed to:
http://dx.doi.org/10.1109/ISAP57493.2023.10389090
Reconfigurable Quad-polarization L-band Antenna October 30, 2023
A low-cost L-band antenna with reconfigurable quad-polarization is presented. The antenna consists of four identical radiating elements. Each element comprises two stacked rectangular patches to achieve more than 10% bandwidth. Through proper phasing of the four elements, the antenna can realize two orthogonal linear polarizations and two circular polarizations. To demonstrate the concept, an antenna is realized using FR-4 substrate. The measured 10-dB input return loss bandwidth is 11%. And the measured 3-dB gain bandwidth is from 1.21 GHz to 1.36 GHz, with a maximum gain of 8.8 dBi for both linear polarization and circular polarization.
Researcher/Author:
Gong Chen, Fujiang Lin & Koen Mouthaan
Published in:
2023 IEEE International Symposium On Antennas And Propagation (ISAP)
This paper introduces a backscattered BLE5 transmitter for low-cost single-antenna green systems solely powered by mm-scale harvesters. Peak power reduction to 10.6 μW is achieved while enabling BLE-compliant spectral mask up to the maximum allowed backscattered power for range extension. Peak power is reduced via an approximate GFSK modulator architecture based on a non-uniform self-sampling digitally controlled oscillator (DCO) with period pruning/clustering, in place of a power-hungry Gaussian filter and PLL used in conventional GFSK modulators. A 180-nm testchip shows 97-m range with commodity receiver at 4X power and 3X range improvement with respect to prior art.
Since heat generation in electronic devices causes thermal failure, heat dissipation is of critical importance. Furthermore, deformable devices are subjected to mechanical stress, therefore, mechanically stable thermal management material should be considered. Herein, a strategy for printable, thermally conductive, and mechanically stable composite ink for thermal management is introduced. Based on the galvanic replacement between eutectic gallium indium (EGaIn) nanoparticles and silver (Ag) flakes, decoration of the EGaIn nanoparticles on Ag flakes is resulted from the difference in standard reduction potential between Ag, Ga, and In. The resultant alloy formation(Ag–Ga or Ag–In) serves as the thermal transport junction between Ag flakes, leading to high thermal and electrical conductivity (≈140 W mK−1 and ≈106 S m−1, respectively). In addition, owing to the polymer binder, the printed ink is mechanically stable on a substrate exhibiting stable thermal conductivity and sheet resistance under the cyclic bending test. Notably, the heat dissipation of the light-emitting diode (LED) showed better performance when applied with the developed composite ink compared to commercial Ag paste and thermal paste. The junction temperature of the LED is reduced effectively, resulting in a longer lifetime of the LED. The thermal management solution can be utilized in next-generation soft electronics.
A 12-bit hybrid SAR ADC with SAR search assisted by comparator offset injection is presented. The proposed ADC architecture reuses offset calibration circuitry for conversion of the last two LSBs, reducing the required capacitive DAC resolution and pushing its total capacitance down to its thermal noise limit. The proposed ADC can be calibrated without requiring any accurate input generation. The prototype ADC, fabricated in 40nm CMOS, occupying an active core area of 0.0315mm2 , and operating at 0.35-0.45V for sampling rates ranging from 0.4 to 80 kS/s respectively, achieves the lowest Walden-FOM between 0.425-0.947fJ/conv-step, with an SNDR > 64.7dB and SFDR > 74.3dB.
First Demonstration of HZO-LNOI Integrated Ferroelectric Electro-Optic Modulator and Memory to Enable Reconfigurable Photonic Systems September 11, 2023
Publication
First Demonstration of HZO-LNOI Integrated Ferroelectric Electro-Optic Modulator and Memory to Enable Reconfigurable Photonic Systems
We have successfully demonstrated, for the first time, an innovative back-end-of-line (BEOL) compatible electro-optic modulator and memory (EOMM) based on Lithium Niobate on Insulator (LNOI) micro-ring resonator (MRR) integrated with Ferroelectric Hafnium Zirconate Hf 0.5 Zr 0.5 O (HZO) non-volatile analog memory. High non-volatile memory and modulation performances are both achieved in a single compact device, exhibiting high extinction ratio of 13.3 dB, excellent efficiency of 66pm/V, stable nine-state switching, record-high endurance exceeding 10 9 cycles.
This is accomplished by utilizing Pockels effect in LNOI, induced by electric-field effect from remnant HZO ferroelectric polarization. We studied the system implementation of reconfigurable chiplet-interposer photonic interconnect, enabled by the EOMM and EOMM with hybrid thermal-optical modulation. Our model shows a potential 70% energy efficiency improvement over conventional electrical interposer interconnect. We have also tested the integration of the EOMM with POET technologies’ 400G Tx/Rx optical interposer chip and studied a limited scale demonstration of the EOMM device.
Cramer-Rao lower bound (CRLB) analysis for estimation of the direction of arrival (DOA) for curved receiving antenna arrays is presented. Software defined radio (SDR) measurements are used to validate the results. First the CRLB for curved arrays is derived. Then the method is applied to case studies using three different arrays for DOA estimation. The arrays with four antennas with different curvatures are fabricated and SDR is used to validate the results. It is found that the performance depends on the DOA, with the curved array providing benefits for certain directions of arrival. The proposed method can help designers of arrays for DOA estimation to improve the performance.
Researcher/Author: Jiahao Wang, Peizhuo Yang and Koen Mouthaan
Published in: IEEE
To download the paper, please proceed to:
https://ieeexplore.ieee.org/document/10237781
A C-band Dual-pol Compact Reflector Antenna with a Square Waveguide Feed September 7, 2023
Publication
A C-band Dual-pol Compact Reflector Antenna with a Square Waveguide Feed
A C-band center-fed compact reflector antenna with dual linear polarization over a bandwidth of 25% is presented. To achieve this bandwidth, the feed uses a square waveguide, a polycarbonate neck, and a hat sub-reflector. The gain of the antenna is between 29 dBi and 32 dBi over the frequency range of 5–6.4 GHz. The main objective of the presented work is to extend the operating bandwidth of the high-gain antenna while keeping the structure of the feed as simple as possible. Measured antenna patterns, gain vs. frequency, cross polarization vs. frequency, and S-parameters of the feed are presented.
Researcher/Author: Su Yee Aye , Peng Khiang Tan , Tse Tong Chia , Sigurd Huber, and Koen Mouthaan
Published in: IEEE
To download the paper, please proceed to:
https://ieeexplore.ieee.org/document/10238085
Deployable L-Band Bowtie Antenna Array for Satellite Applications September 7, 2023
Publication
Deployable L-Band Bowtie Antenna Array for Satellite Applications
A stowable and deployable 4×4 bowtie array at L-band is presented. The 16 bowtie antennas are fabricated using standard FR-4. The bowtie array uses flexible copper-clad kapton with supporting narrow aluminum channels to replace the conventional rigid ground plane. A size reduction of about 85% is achieved when the antenna is stowed. The measured gain, excluding the losses of the feed network, is between 16 dBi and 19.5 dBi over the frequency band of interest from 1.2 GHz to 1.5 GHz.
Researcher/Author: Gong Chen, Fujiang Lin, and Koen Mouthaan
Resilient conductive membrane synthesized by in-situ polymerisation for wearable non-invasive electronics on moving appendages of cyborg insect September 1, 2023
Publication
Resilient conductive membrane synthesized by in-situ polymerisation for wearable non-invasive electronics on moving appendages of cyborg insect
By leveraging their high mobility and small size, insects have been combined with microcontrollers to build up cyborg insects for various practical applications. Unfortunately, all current cyborg insects rely on implanted electrodes to control their movement, which causes irreversible damage to their organs and muscles. Here, we develop a non-invasive method for cyborg insects to address above issues, using a conformal electrode with an in-situ polymerized ion-conducting layer and an electron-conducting layer. The neural and locomotion responses to the electrical inductions verify the efficient communication between insects and controllers by the non-invasive method. The precise “S” line following of the cyborg insect further demonstrates its potential in practical navigation. The conformal non-invasive electrodes keep the intactness of the insects while controlling their motion. With the antennae, important olfactory organs of insects preserved, the cyborg insect, in the future, may be endowed with abilities to detect the surrounding environment.
Researcher/Author:
Qifeng Lin, Rui Li, Feilong Zhang, Kazuki Kai1, Zong Chen Ong, Xiaodong Chen and Hirotaka Sato
Mechanically compliant conductors are of utmost importance for the emerging fields of soft electronics and robotics. However, the development of intrinsically deformable organic conductors remains a challenge due to the trade-off between mechanical performance and charge mobility. In this study, we report a solution to this issue based on size-selective ionic crosslinking. This rationally designed crosslinking mediated by length-regulated oligo(ethylene glycol) pendant groups and metal ions simultaneously improved the softness and toughness and ensured excellent mixed ionic–electronic conductivity in poly(3,4-ethylenedioxythiophene):polystyrene sulfonate composite materials. Moreover, the added ions remarkably promoted accumulation of charge carriers in response to temperature gradient, thus offering a viable approach to stretchable thermoelectric generators with enhanced stability against humidity.
Researcher/Author: Junwoo Lee, Hyunwoo Bark, Yazhen Xue, Pooi See Lee, and Mingjiang Zhong*
Published in: Angewandte Chemie International Ed. 2023
