Bidirectional Circuits Research Articles

Unified Modeling, Analysis, and Design of Isolated Bidirectional CLLC Resonant DC–DC Converters

Due to the bidirectional power transmission, high power density, and high efficiency, bidirectional CLLC resonant converters are attracting more and more research attention in electric vehicles and energy storage systems. However, the existing models are difficult to unify the bidirectional circuits to analyze and design the circuit factors, and thus the parameter design approach and bidirectional synchronous rectification (SR) become rather complex and cumbersome. Especially in asymmetric parameter design, a lot of calculations or iterations are needed, which seriously increase the difficulty of design. To address this concern, a bidirectional unified modeling, analysis, and design method is proposed in this article. By selecting appropriate and quantitative bidirectional circuit factors, this model unifies the forward and reverse circuits and establishes the relationship between them, which greatly simplifies the calculation or iteration of the parameter design and the complexity of bidirectional SR. In addition, this parameter design method makes the bidirectional gain reach a higher range and reduces the range of bidirectional switching frequency. Finally, this unified modeling, analysis, and design method is verified in bidirectional CLLC resonant converters including symmetrical full-bridge, asymmetrical full-bridge, symmetrical half-bridge, and asymmetrical half-bridge CLLC, respectively.

A Single-Phase Five-Level Transformer-Less PV Inverter for Leakage Current Reduction

Multilevel inverters are becoming more and more popular in photovoltaic applications because of lower total harmonic distortion, lower switching stress and lower electromagnetic interference. In this article, a single-phase five-level transformer-less PV inverter is proposed for the purpose of leakage current reduction. The inverter is based on a flying capacitor (FC) configuration, the voltages of FCs are balanced at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">V</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> /4 through the coordination of the two half-bridge at the switching frequency, helps to reduce investment cost in passive elements. Two bidirectional circuits are added to guarantee a constant common-mode (CM) voltage. The leakage current elimination mechanism is analyzed in detail with operational states and CM equivalent model. The losses are analyzed, the control strategy and the FCs are detailed designed. A comparison is also made in terms of the number of elements, voltage stress and CM voltage. Experiment results under grid-connected condition show that the proposed topology achieves both excellent differential-mode and CM performance.

Neuroimmune regulatory networks of the airway mucosa in allergic inflammatory disease.

Communication between the nervous and immune systems serves a key role in host‐protective immunity at mucosal barrier sites including the respiratory tract. In these tissues, neuroimmune interactions operate in bidirectional circuits that can sense and respond to mechanical, chemical, and biologic stimuli. Allergen‐ or helminth‐induced products can produce airway inflammation by direct action on nociceptive afferents and adjacent tissues. The activity of nociceptive afferents can regulate innate and adaptive immune responses via neuropeptides and neurotransmitter signaling. This review will summarize recent work investigating the role of neuropeptides CGRP, VIP, neuromedins, substance P, and neurotransmitters dopamine and the B2‐adrenoceptor agonists epinepherine/norepinepherine, each of which influence type 2 immunity by instructing mast cell, innate lymphoid cell type 2, dendritic cell, and T cell responses, both in the airway and the draining lymph node. Afferents in the airway also contain receptors for alarmins and cytokines, allowing their activity to be modulated by immune cell secreted products, particularly those secreted by mast cells. Taken together, we propose that further investigation of how immunoregulatory neuropeptides shape respiratory inflammation in experimental systems may reveal novel therapeutic targets for addressing the increasing prevalence of chronic airway disease in humans.

A 28.16-Gb/s Area-Efficient 60-GHz CMOS Bidirectional Transceiver for IEEE 802.11ay

This article presents a 60-GHz CMOS transceiver designed for IEEE 802.11ay. To reduce the manufacturing cost, an area-efficient bidirectional technique is utilized in this work. The proposed bidirectional amplifier allows the sharing of interstage passive components. A five-stage power-amplifier (PA)-low-noise-amplifier (PA-LNA) designed based on the proposed bidirectional amplifier occupies less than half on-chip area, while staying a similar performance with the conventional standalone PA-LNA. Considering the multiple-in–multiple-out (MIMO) configuration, this work integrates two transceiver elements in the same chip. Thanks to the area-efficient bidirectional circuits, the transceiver in this work only requires 0.96-mm2 core area including the quadrature upconversion and downconversion. The occupied core area for a five-stage PA-LNA is 0.44 mm2. The measured noise figure for the proposed transceiver in RX mode is 5.4 dB at 60 GHz. The measured TX-mode error vector magnitude (EVM) is −26 dB in 64 quadrature amplitude modulation (QAM) with an output power of −4.2 dBm. This work realizes a maximum data rate of 28.16 Gb/s in 16-QAM. A 64-QAM two-channel-bonding data rate of 21.12 Gb/s is also achieved by the transceiver with a −22.5-dB TX-to-RX EVM. The power consumptions are 94 mW in TX mode and 105 mW in RX mode.

Novel connections and precision approaches.

Research in mucosal immunology has continued to generate exciting advances in cellular and molecular biology and to pave the way for a better understanding of human health and disease. In 2018, numerous groups defined bidirectional circuits of communication between the mucosal immune system, non-haematopoietic cell types and microbial communities, while also developing precision approaches to define and manipulate host–microbiota interactions in the gut. Recent research in mucosal immunology has uncovered novel lines of communication between the mucosal immune system and other cellular and metabolic pathways. Given the complexity of these networks, new precision approaches are being developed to dissect the contribution of specific pathways or selected microorganisms.

Optimizing Online Permutation-Based AE Schemes for Lightweight Applications

We explore ways to optimize online, permutation-based authenticated encryption (AE) schemes for lightweight applications. The lightweight applications demand that AE schemes operate in resource-constrained environments, which raise two issues: 1) implementation costs must be low, and 2) ensuring proper use of a nonce is difficult due to its small size and lack of randomness. Regarding the implementation costs, recently it has been recognized that permutation-based (rather than block-cipher-based) schemes frequently show advantages. However, regarding the security under nonce misuse, the standard permutation-based duplex construction cannot ensure confidentiality. There exists one permutation-based scheme named APE which offers certain robustness against nonce misuse. Unfortunately, the APE construction has several drawbacks such as ciphertext expansion and bidirectional permutation circuits. The ciphertext expansion would require more bandwidth, and the bidirectional circuits would require a larger hardware footprint. In this paper, we propose new constructions of online permutation-based AE that require less bandwidth, a smaller hardware footprint and lower computational costs. We provide security proofs for the new constructions, demonstrating that they are as secure as the APE construction.

Backscattering in silicon microring resonators: a quantitative analysis

AbstractSilicon microring resonators very often exhibit resonance splitting due to backscattering. This effect is hard to quantitatively and predicatively model. This paper presents a behavioral circuit model for microrings that quantitatively explains the wide variations in resonance splitting observed in experiments. The model is based on an in‐depth analysis of the contributions to backscattering by both the waveguides and couplers. Backscattering transforms unidirectional microrings into bidirectional circuits by coupling the clockwise and counterclockwise circulating modes. In high‐Q microrings, visible resonance splitting will be induced, but, due to the stochastic nature of backscattering, this splitting is different for each resonance. Our model, based on temporal coupled mode theory, and the associated fitting method, are both accurate and robust, and can also explain asymmetrically split resonances. The cause of asymmetric resonance splitting is identified as the backcoupling in the couplers. This is experimentally confirmed and its dependency on gap and coupling length is further analyzed. Moreover, the wide variation in resonance splitting of one spectrum is analyzed and successfully explained by our circuit model that incorporates most linear parasitic effects in the microring. This analysis uncovers multi‐cavity interference within the microring as an important source of this variation. image

Implantable neurotechnologies: bidirectional neural interfaces--applications and VLSI circuit implementations.

A bidirectional neural interface is a device that transfers information into and out of the nervous system. This class of devices has potential to improve treatment and therapy in several patient populations. Progress in very large-scale integration has advanced the design of complex integrated circuits. System-on-chip devices are capable of recording neural electrical activity and altering natural activity with electrical stimulation. Often, these devices include wireless powering and telemetry functions. This review presents the state of the art of bidirectional circuits as applied to neuroprosthetic, neurorepair, and neurotherapeutic systems.

Activation of the sympathetic nervous system mediates hypophagic and anxiety-like effects of CB 1 receptor blockade

Complex interactions between periphery and the brain regulate food intake in mammals. Cannabinoid type-1 (CB1) receptor antagonists are potent hypophagic agents, but the sites where this acute action is exerted and the underlying mechanisms are not fully elucidated. To dissect the mechanisms underlying the hypophagic effect of CB1 receptor blockade, we combined the acute injection of the CB1 receptor antagonist rimonabant with the use of conditional CB1-knockout mice, as well as with pharmacological modulation of different central and peripheral circuits. Fasting/refeeding experiments revealed that CB1 receptor signaling in many specific brain neurons is dispensable for the acute hypophagic effects of rimonabant. CB1 receptor antagonist-induced hypophagia was fully abolished by peripheral blockade of β-adrenergic transmission, suggesting that this effect is mediated by increased activity of the sympathetic nervous system. Consistently, we found that rimonabant increases gastrointestinal metabolism via increased peripheral β-adrenergic receptor signaling in peripheral organs, including the gastrointestinal tract. Blockade of both visceral afferents and glutamatergic transmission in the nucleus tractus solitarii abolished rimonabant-induced hypophagia. Importantly, these mechanisms were specifically triggered by lipid-deprivation, revealing a nutrient-specific component acutely regulated by CB1 receptor blockade. Finally, peripheral blockade of sympathetic neurotransmission also blunted central effects of CB1 receptor blockade, such as fear responses and anxiety-like behaviors. These data demonstrate that, independently of their site of origin, important effects of CB1 receptor blockade are expressed via activation of peripheral sympathetic activity. Thus, CB1 receptors modulate bidirectional circuits between the periphery and the brain to regulate feeding and other behaviors.

Bipolar Narrow-Pulse Generator With Energy-Recovery Feature for Liquid-Food Sterilization

This paper presents a bipolar narrow-pulse generator with energy-recovery feature for liquid-food sterilization. The generator is formed from a bidirectional flyback converter and active-clamp circuits which are further simplified to the proposed topology with the synchronous-switch technique. In the converter, the leakage inductance of the transformer will resonate with the active-clamp capacitors to recover the trapped energy and to reduce switching loss, improving efficiency by about 13%. In addition, the capacitors can reduce voltage stress significantly. Experimental results obtained from a prototype with the output of plusmn6-20 kV, depending on loads, and the peak power of 1.2 MW has confirmed these discussions.

Hypothalamic-pituitary-thyroid axis and the immune system.

The paper reviews data on bidirectional circuits between the hypothalamic-pituitary-thyroid (HPT) axis and the immune system. The effects of thyroliberin (TRH), thyrotropin (TSH) and of thyroid hormones (thyroxine and triiodothyronine) on the immune system, as well as the effects of mono- and lymphokines on the HPT axis are discussed.

Weight Perturbation: An Optimal Architecture and Learning Technique for Analog VLSI Feedforward and Recurrent Multilayer Networks.

Previous work on analog VLSI implementation of multilayer perceptrons with on-chip learning has mainly targeted the implementation of algorithms like backpropagation. Although backpropagation is efficient, its implementation in analog VLSI requires excessive computational hardware. In this paper we show that, for analog parallel implementations, the use of gradient descent with direct approximation of the gradient using "weight perturbation" instead of backpropagation significantly reduces hardware complexity. Gradient descent by weight perturbation eliminates the need for derivative and bidirectional circuits for on-chip learning, and access to the output states of neurons in hidden layers for off-chip learning. We also show that weight perturbation can be used to implement recurrent networks. A discrete level analog implementation showing the training of an XOR network as an example is described.

Evidence that thymosins and other biologic response modifiers can function as neuroactive immunotransmitters

An increasing amount of data supports the hypothesis that there are bidirectional circuits between the central nervous system (CNS) and the immune system. Soluble products that appear to transmit information from the immune compartment to the CNS include thymosins, lymphokines, and certain complement proteins. Opioid peptides, adrenocorticotropic hormone (ACTH), and thyroid-stimulating hormone (TSH) are additional products of lymphocytes that may function in immunomodulatory neuroendocrine circuits. It is proposed that the term "immunotransmitter" be used to describe molecules that are produced predominantly by cells that comprise the immune system but that transmit specific signals and information to neurons and other cell types. Examples would include thymosin alpha 1 and beta 4, lymphocyte-derived ACTH, TSH, and beta-endorphin, interleukin 1, interferon as well as certain other lymphokines and cytokines. The evidence that certain thymosin peptides can serve as immunotransmitters by modulating the hypothalamic-pituitary-adrenal and gonadal axes will be discussed.