Double Feedback Research Articles

A highly efficient adaptive body bias CMOS rectifier with double-side feedback at a tone of 2.4 GHz

ABSTRACT In this paper, a highly efficient adaptive body bias CMOS rectifier employed with double side feedback, operating with 2.4 GHz frequency, is proposed for radio frequency energy harvesting. The proposed circuit is built with 45 nm TSMC CMOS technology. In the suggested architecture, the double side feedback along with body bias is used to regulate threshold voltage. The use of PMOS transistors as a diode in reverse bias configuration has restricted the reverse current without compromising the forward current. This design has gained a maximum PCE of 82.25% and 77.29% at an input power of −23.90dBm and −23.74dBm and 500K and 100K load, respectively. The circuit has maintained a wide dynamic range of 30dbm at PCE >30% and registered an input sensitivity of −10.07dBm for attaining a DC output voltage of 1 V as compared to the previous works.

INCAPE23-Design of Class E CMOS Power Amplifier with Integrated Active Inductor for 5G Applications

This paper presents a design of class E power amplifier (PA) with integrated active inductor for 5G applications. A high Q-factor active inductor (AI) is proposed utilizing CMOS 0.18-µm technology. A Gyrator-C based is employed to realize an active inductor with a double cascode resistive feedback configuration. The biasing voltage of 1.21 V, current source of 0.5 mA and supply voltage of 2.5 V is used. In order to obtain high efficiency, the proposed AI is implemented in a class E power amplifier by replacing on of the spiral inductors. According to the simulation results, the proposed AI can reach a high Q-factor of 50,000 and an inductance of 2.03 nH at 3.5 GHz. The power added efficiency (PAE) of CMOS class E PA with integrated AI, according to simulation result, is 72 % at 3.5 GHz. The intended PA's PAE was dramatically raised by the class E AI that was built.

Pitching Stabilization Control for Super Large Ships Based on Double Nonlinear Positive Feedback under Rough Sea Conditions

Due to the rapid development of a global navigation satellite system and the rapid growth of ships, the traditional control algorithms are not suitable; hence, the longitudinal rocking phenomenon generated by external disturbances is more serious when a ship is sailing. This paper takes a mathematical model of the super large oil tanker “KVLCC2”’s longitudinal motion as the controlled plant, establishing a multi-input multi-output instability control system, using the root trajectory shaping method and a weighting matrix to ensure the stability of its transfer function’s mathematical model. An improved closed-loop gain-shaping algorithm is utilized to design a simple robust controller. And a dual nonlinear positive feedback control algorithm is added to the control system to further improve the controller’s pitching stabilization performance and reduce the controller’s output energy. In order to verify that the controller has a consistently strong robustness, simulation experiments are carried out by adding a level 6, 7 and 8 wind wave model and a perturbation link to the control system, respectively. The results show that when the value of the hysteresis constant is taken as 0.25, the output values of the heave displacement and the pitch angle are greatly reduced, and the longitudinal rocking phenomenon is significantly improved. The dual nonlinear positive feedback control algorithm enhances the ship’s pitching stabilization control capability and further reduces the controller’s output energy, which provides technical support for the smooth and efficient sailing of super large ships under changing sea conditions. Combined with a global navigation satellite system, this algorithm provides a new method for pitching stabilization control of super large ships.

Dynamic response and stability analysis of vehicle systems with double time-delay feedback control

In this paper, the vehicle suspension dynamic response of time delay feedback control is analyzed considering the suspension of the seat. An active suspension vibration reduction control method based on double time-delay feedback control is proposed to further improve the ride comfort. Firstly, the double time-delay dynamic response equation of the system with three degrees of freedom is established. Then, the root mean square values of seat acceleration and body acceleration are used as the objective functions. Meanwhile, the RMS values of suspension dynamic deflection and tire dynamic displacement are used as constraints, and the optimal feedback parameters are obtained using particle swarm optimisation. The Routh-Hurwitz criterion and frequency domain scanning methods are used to verify the stability of the double time-delay system. Finally, simulation in the time domain and frequency domain is accomplished. It is verified that this feedback control method has strong robustness and anti-interference ability.

Gaussian bistable cascade double feedback stochastic resonance weak signal enhancement detection

Stochastic resonance (SR), as a nonlinear weak signal enhancement detection method, has found extensive applications in fields like fault diagnosis and biological information processing. However, further research has revealed that single stochastic resonance systems often fail to meet the requirements of practical engineering applications, leading to a growing interest in multi-system collaborative stochastic resonance. This article first constructs a cascaded SR system based on the Gaussian bistable model, and introduces the idea of feedback into the cascaded system. A Gaussian bistable cascaded dual feedback SR system is proposed to improve the output signal enhancement performance of the system. This system effectively utilizes the memory characteristics inherent in the output feedback and enables multi-level particle transitions and energy transfers in noisy input signals, thereby reducing noise and enhancing the extraction of weak signal features. Furthermore, the BSO optimization algorithm was utilized to optimize the system parameters of the model, resulting in an adaptive Gaussian bistable cascaded double feedback stochastic resonance (GBCDFSR) system. This system is applied to the processing of noisy periodic signals across various noise types. Simulation experiments and engineering applications show that the proposed model has stronger signal detection capabilities.

Enhancement of quantum entanglement between twin beams via a four-wave mixing process with double feedback

Two-port feedback has been theoretically studied and proved to be effective in enhancing the degree of entanglement of the output beams for a four-wave mixing process. Here, to further consider the loss effects and phase delays, we use a model that is closer to practical implementation. By reasonably tuning the feedback coefficients, we find that a higher degree of entanglement and higher power of the output beams can be achieved, and a loose requirement for phase-locking accuracy can be obtained. This scheme may have promising applications in practical quantum computation and quantum communication.

The transcription factor OCT6 promotes the dissolution of the naïve pluripotent state by repressing Nanog and activating a formative state gene regulatory network

In the mouse embryo, the transition from the preimplantation to the postimplantation epiblast is governed by changes in the gene regulatory network (GRN) that lead to transcriptional, epigenetic, and functional changes. This transition can be faithfully recapitulated in vitro by the differentiation of mouse embryonic stem cells (mESCs) to epiblast-like cells (EpiLCs), that reside in naïve and formative states of pluripotency, respectively. However, the GRN that drives this conversion is not fully elucidated. Here we demonstrate that the transcription factor OCT6 is a key driver of this process. Firstly, we show that Oct6 is not expressed in mESCs but is rapidly induced as cells exit the naïve pluripotent state. By deleting Oct6 in mESCs, we find that knockout cells fail to acquire the typical morphological changes associated with the formative state when induced to differentiate. Additionally, the key naïve pluripotency TFs Nanog, Klf2, Nr5a2, Prdm14, and Esrrb were expressed at higher levels than in wild-type cells, indicating an incomplete dismantling of the naïve pluripotency GRN. Conversely, premature expression of Oct6 in naïve cells triggered a rapid morphological transformation mirroring differentiation, that was accompanied by the upregulation of the endogenous Oct6 as well as the formative genes Sox3, Zic2/3, Foxp1, Dnmt3A and FGF5. Strikingly, we found that OCT6 represses Nanog in a bistable manner and that this regulation is at the transcriptional level. Moreover, our findings also reveal that Oct6 is repressed by NANOG. Collectively, our results establish OCT6 as a key TF in the dissolution of the naïve pluripotent state and support a model where Oct6 and Nanog form a double negative feedback loop which could act as an important toggle mediating the transition to the formative state.

Development of undulator motion control system with redundant protections

The undulator is a key luminous component of the Shanghai high repetition rate x-ray free electron laser and extreme light facility, and the motion control system is an important part of the undulator. The main task of the motion control system is to complete the high precision adjustment of the gap and taper between the upper magnetic pole girder and lower magnetic pole girder, so as to adjust the wavelength of the radiation light. According to the development requirements of the motion control system for the U26 undulator, which is a conventional permanent magnet, this paper proposes a new motion control system with double position feedback closed-loop control, including programmable logic controller (PLC) closed-loop control based on position feedback by a linear absolute encoder (LAE) and driver closed-loop control based on position feedback by a rotary absolute encoder (RAE) of a servo motor. Multiple motion tests of the U26 undulator have shown that the repeatability accuracy of the gap is ±50 nm and the gap drive can reach 0.1 µm step size, the error of which is about ±20 nm according to the feedback of the LAE. The conclusion can be drawn that the motion step size and repeatability accuracy of the motion control system for the U26 undulator are improved by one order of magnitude on the basis of meeting all technical requirements. At the same time, motor torque protection, motor temperature protection, and redundant position protection with RAE can further improve the reliability and safety of the motion control system for the U26 undulator.

Abstract 4455: Metabolic stress induces a double positive feedback loop between AMPK and p62 conferring dual activation of AMPK and NRF2 to synergize antioxidant defense

Abstract Co-occurring mutations in KEAP1 in LKB1-mutant NSCLC activate NRF2 to compensate losing LKB1-AMPK activity during metabolic adaptation and survival. Here, we investigated the regulatory crosstalk between LKB1-AMPK and KEAP1-NRF2 pathways during metabolic stress. We found that metabolic stress activates NRF2 through the expression and phosphorylation of p62, causing the autophagic degradation of KEAP1. Intriguingly, the induction of p62 during metabolic stress is also required to activate AMPK by promoting AXIN-LKB1-AMPK complex formation and recruiting it to the lysosomal membrane. Importantly, the p62-driven dual-activation of AMPK and NRF2 was critical for tumour growth by synergizing antioxidant defences. In turn, the induction of p62 also required LKB1-AMPK activity, suggesting a double positive feedback loop between AMPK and p62. Mechanistically, the increase in lysosomal pH caused by low glucose metabolism and AMPK-dependent reduction of proton generation induced PP2A-dependent dephosphorylation of TFEB/TFE3 which increased the expression of p62. The increase of ROS caused by metabolic stress induced lysosomal MCOLN1-Ca2+ dependent activation of TAK1 which increased p62 phosphorylation. Protons provided by lactic acid abrogated all the effects caused by metabolic stress. This positive feedback loop between AMPK and p62 that activates AMPK and NRF2 can potentially explain why co-occurring mutations in LKB1 and KEAP1 occur and further provide promising therapeutic strategies for lung cancer. Citation Format: Eun-Ji Choi, Hyun-Taek Oh, Seon-Hyeong Lee, Chen-Song Zhang, Mengqi Li, Soo-Youl Kim, Sunghyouk Park, Tong-Shin Chang, Byung-Hoon Lee, Sheng-Cai Lin, Sang-Min Jeon. Metabolic stress induces a double positive feedback loop between AMPK and p62 conferring dual activation of AMPK and NRF2 to synergize antioxidant defense [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4455.

Design and performance analysis of tri-layered strained Si/Si1–x Ge x /Si heterostructure DG feedback FET

This work presents the design and performance analysis of a tri-layered strained Si/Si1−x Ge x /Si heterostructure double gate feedback field-effect transistor (DG FBFET). The proposed DG FBFET is designed by introducing biaxial strain in the device by sandwiching a Si1−x Ge x layer between two thin Si layers to provide high ON current as well as ultra-steep switching characteristics. The device offers a significantly high ON current (3.4 x 10−3 A/μm), high I ON /I OFF ratio (∼1010), a large memory window of 1.06 V, and an extremely low subthreshold swing (∼0.3 μ V/decade), which can be very useful for memory and neuromorphic applications. Furthermore, the ON/OFF switching of the device has been accomplished at a lower threshold voltage (0.287 V), allowing it to be utilized in low-power electronics. Synopsys TCAD tool has been used to create the device structure and analyze the electrical performances of the device.

Design and performance analysis of Si-SiGe heterostructure based double gate feedback FET

The design and performance analysis of a Si-SiGe heterostructure-based double gate feedback field-effect transistor (HDG FBFET) are presented in this paper. The proposed HDG FBFET is capable of providing high on current (3 × 10−4 A/μm) with a large I ON /I OFF ratio (3 × 1011) and is scalable up to 20 nm channel length. Its exceptionally steep switching characteristics (SS < 1 mV/decade) and ability to switch ON/OFF at lower gate voltage due to the use of smaller band-gap material (Si1−x Ge x ) in channel-2 and drain regions make it suitable for use in low power applications. A significant hysteresis window of 4.99 V is also achieved by the device, which can be extremely helpful for memory applications. Moreover, a comprehensive investigation of the nature of hysteresis in relation to the different device parameters has also been carried out. The designing of the device structure and all of the electrical performance characterization have been done using the Sentaurus TCAD tool.

Double feedback control-based [formula omitted] admissibilization for hybrid descriptor systems subject to external impulses and fast varying delays

This paper is concerned with the H∞ admissibilization for hybrid descriptor systems subject to external impulses, Markovian jumping and fast varying delays characteristics by virtue of designing double feedback controllers. The neoteric double feedback controllers are composed of normal state feedback controller and impulsive controller, not only the internal impulses can be eliminated, but also the external destabilizing impulses can be overcome and state jumps at switching instants can be suppressed. Impulse time dependent, delays dependent and Markovian jump modes dependent Lyapunov–Krasovskii functional is developed, and the improved free-weight matrix technique is employed to effectively capture the hybrid characteristics and realize the innovative conditions of H∞ admissibilization for descriptor impulsive Markovian jump systems with fast varying delays. By utilizing M-P matrix inversion approach and matrix transformation technology, the desired double feedback controllers gains are acquired in terms of linear matrix inequalities. RLC electrical circuit system is applied to demonstrate the availability and practicability of the addressed designing schemes.

Double closed-loop feedback control strategy for enhanced external counterpulsation to regulate hemodynamic response of human common carotid artery

Enhanced external counterpulsation (EECP) is a mechanical therapy for the clinical management of ischemic cardio-cerebrovascular diseases. Applying different EECP modes to different patients would be based on the experience of physicians. Existing hemodynamic models could describe the quantitative relationship between different EECP modes and hemodynamic parameters of specific parts of human blood circulatory system. However, currently there is no closed-loop control system available for precisely, personally, and intelligently performing the EECP. Therefore, to significantly improve the clinical benefits of rehabilitation treatment of ischemic cardio-cerebrovascular diseases with the EECP, this study developed a double closed-loop physiological control algorithm for the EECP device. Firstly, a detailed lumped parameter model describing the hemodynamics of human blood circulatory system was updated based on the available models; then the EECP device was coupled to it and the updated model was tested with the clinical data; finally, a double closed-loop feedback control strategy for precise regulation of the carotid hemodynamic response by the EECP was proposed. The control objectives were to maintain the mean arterial pressure and EECP pressure amplitude of patients with two gain-scheduled proportional-integral (PI) controllers. In-silico results showed that the clinical data can prove the accuracy of the updated model, and the appropriate EECP pressure amplitude could provide patients with the best benefits. The proposed control system could generate satisfied hemodynamic effects even with noise, demonstrating its feasibility and robustness. It is also easy to apply with high accuracy, and may be the effective solutions for developing intelligent and personalized EECP devices.

Deterministic and stochastic approaches to a minimal model for the transition from autophagy to apoptosis.

Autophagy and apoptosis are crucial cellular mechanisms. The cytoprotective function of autophagy is mediated by the negative regulation of apoptosis, which in turn inhibits autophagy. Although research into the molecular connection between autophagy and apoptosis is booming, the intricate regulatory mechanisms of this process are still not completely understood. Therefore, the objective of this study was to develop a minimal model to explore the transition from autophagy to apoptosis. This biological system was analyzed by comprehensively integrating both the deterministic and the stochastic dynamics of the cells. The system exhibited bistability, and the statistical properties of cells undergoing autophagy and apoptosis were analyzed at two different stress levels with varying noise strengths. Moreover, we investigated how noise affected the double negative feedback loops between autophagy and apoptosis and further triggered transitions at two different stress levels and initial conditions. Finally, the effect of noise on transition was comprehensively studied under continuous stress variations and the two different initial conditions, showing that stronger noise results in more randomness during the switching process. Our work may provide novel insights for further experiments and modeling.

Dynamics of Semiconductor Laser Coupled with Two External Cavities

An investigation into the dynamic states and relative intensity noise of laser diodes subjected to double optical feedback has been conducted. We employed modified and improved time-delay rate equations to account for double external optical feedback. The dynamic states and noise of lasers will be investigated using bifurcation diagrams of the output photon number, its temporal variations, and the intensity noise of the laser. This analysis considers feedback strengths due to the double external cavity and their spacing from the front facet of the laser with and without phase due to feedback. The results reveal that considering phase causes significant variations in laser intensity and a phase shift in the temporal variations of the laser output. This results in relative intensity noise suppression and a frequency shift in the intensity noise spectrum. These findings represent new contributions to our understanding of the reliance of lasing frequency shift on the phase due to feedback, regardless of whether feedback originates from a single or double external cavity. We investigated the optimal conditions corresponding to stable dynamic states of the laser with the lowest noise level. Additionally, we identified conditions that result in chaotic dynamics, where the spectrum does not convey information about the laser system. These insights have potential applications in chaotic and secure optical data encryption.

Dynamic performance of terahertz quantum cascade laser with double optical feedbacks: Role of the external cavity

The dynamic performance of a terahertz (THz) quantum cascade laser (QCL) with double optical feedbacks (DOFs) is carefully studied within the framework of single-mode rate equations. The results have shown that the system displays three types of nonlinear dynamic phenomena under the control of different feedback strengths, which are envelope oscillations, spiking oscillations, and high-frequency small-amplitude oscillations, respectively. The fundamental frequency of oscillation is related to the ratio of the round-trip times from two external cavities and the ratio of their feedback strengths. By solving the steady-state equations, we find that the high-frequency, small-amplitude oscillations arise because a pair of modes appear at almost the same point. The output performance of THz QCL system is also studied with square wave signal modulation. The results show that the fundamental frequency of oscillation at the output is only related to the frequency of the square wave signal. And low frequency fluctuations (LFFs) dynamics can be excited by combination of DOFs and adjusting the duty cycle of the square wave signal. This work provides a novel insight into high data-bit THz communication based on QCLs.

Loss minimization in Quadratic Boost Converter Multilevel Inverter fed induction motor system by Tuning of FOPID controller using PSO

Particle swarm optimization algorithm (PSO) is suggested to discover fractional order PID (FOPID) controller optimal variables for a better performance of induction motor. This PSO algorithm is designed to handle multiple optimization issues, due to its ease of application. A Closed Loop Quadratic Boost Converter Multilevel Inverter Fed Induction Motor (QBCMLIIM) system is simulated to earn reduced switching losses and reduced THD by incorporating particle swarm optimization(PSO) tuned Fractional Order PID controller. PSO stands to be one of the popular Artificial Intelligence (AI) method. The PSO algorithm starts its process from the initial particles by allotting initial velocities to the particles. At each location the objective function and the corresponding best values are evaluated. The double loop feedback system enhances the performance and robustness by suppressing the oscillations and overshoots.

Excellent predictive-performances of photonic reservoir computers for chaotic time-series using the fusion-prediction approach.

In this work, based on two parallel reservoir computers realized by the two polarization components of the optically pumped spin-VCSEL with double optical feedbacks, we propose the fusion-prediction scheme for the Mackey-Glass (MG) and Lorenz (LZ) chaotic time series. Here, the direct prediction and iterative prediction results are fused in a weighted average way. Compared with the direct-prediction errors, the fusion-prediction errors appear great decrease. Their values are far less than the values of the direct-prediction errors when the iteration step-size are no more than 15. By the optimization of the temporal interval and the sampling period, under the iteration step-size of 3, the fusion-prediction errors for the MG and LZ chaotic time-series can be reduced to 0.00178 and 0.004627, which become 8.1% of the corresponding direct-prediction error and 28.68% of one, respectively. Even though the iteration step-size reaches to 15, the fusion-prediction errors for the MG and LZ chaotic time-series can be reduced to 55.61% of the corresponding direct-prediction error and 77.28% of one, respectively. In addition, the fusion-prediction errors have strong robustness on the perturbations of the system parameters. Our studied results can potentially apply in the improvement of prediction accuracy for some complex nonlinear time series.

Robust Cascade Control inside a New Model-Matching Architecture

Whenever additional states of a plant can be measured, closing nested feedback loops can be exploited in a variety of ways. The goal here is to reduce the bandwidth of feedback controllers and thus reduce the amplification of sensor noise that can otherwise spoil the expected performance when the actuator saturates. This can be particularly relevant for demanding tracking specifications and large plant uncertainties. In this context, the current work proposes a novel model-matching control architecture with a feedforward controller and two feedback controllers, which is accompanied by a new robust design method in the frequency domain of Quantitative Feedback Theory (QFT). The use of a feedforward controller reduces the amount of feedback to the minimum necessary to constrain the spread of the tracking error responses as specified. Furthermore, this amount of feedback is quantitatively distributed along the frequency between the inner and outer loops to reduce the total sensor noise at the control input as much as possible. A theoretical example illustrates the method and highlights the advantages of the new architecture over two other previously feasible QFT solutions: one with double feedback and another with single feedback plus feedforward. The importance of choosing the correct switching frequency between loops is also demonstrated. Finally, the angle of rotation of a commercial servo motor is successfully controlled using the motor speed as an internal measure.

Multilayer time delay reservoir with double feedback loops for time series forecasting task

Multilayer time delay reservoir with double feedback loops for time series forecasting task