Tunable Inductor Research Articles

A Neuron-Optimized CRISPR/dCas9 Activation System for Robust and Specific Gene Regulation.

CRISPR-based technology has provided new avenues to interrogate gene function, but difficulties in transgene expression in post-mitotic neurons has delayed incorporation of these tools in the central nervous system (CNS). Here, we demonstrate a highly efficient, neuron-optimized dual lentiviral CRISPR-based transcriptional activation (CRISPRa) system capable of robust, modular, and tunable gene induction and multiplexed gene regulation across several primary rodent neuron culture systems. CRISPRa targeting unique promoters in the complex multi-transcript gene brain-derived neurotrophic factor (Bdnf) revealed both transcript- and genome-level selectivity of this approach, in addition to highlighting downstream transcriptional and physiological consequences of Bdnf regulation. Finally, we illustrate that CRISPRa is highly efficient in vivo, resulting in increased protein levels of a target gene in diverse brain structures. Taken together, these results demonstrate that CRISPRa is an efficient and selective method to study gene expression programs in brain health and disease.

Design and Fabrication of Heterogeneous, Deformable Substrates for the Mechanically Guided 3D Assembly.

Development of schemes to form complex three-dimensional (3D) mesostructures in functional materials is a topic of broad interest, thanks to the ubiquitous applications across a diversity of technologies. Recently established schemes in the mechanically guided 3D assembly allow deterministic transformation of two-dimensional structures into sophisticated 3D architectures by controlled compressive buckling resulted from strain release of prestretched elastomer substrates. Existing studies mostly exploited supporting substrates made of homogeneous elastomeric material with uniform thickness, which produces relatively uniform strain field to drive the 3D assembly, thus posing limitations to the geometric diversity of resultant 3D mesostructures. To offer nonuniform strains with desired spatial distributions in the 3D assembly, this paper introduces a versatile set of concepts in the design of engineered substrates with heterogeneous integration of materials of different moduli. Such heterogeneous, deformable substrates can achieve large strain gradients and efficient strain isolation/magnification, which are difficult to realize using the previously reported strategies. Theoretical and experimental studies on the underlying mechanics offer a viable route to the design of heterogeneous, deformable substrates to yield favorable strain fields. A broad collection of 3D mesostructures and associated heterogeneous substrates is fabricated and demonstrated, including examples that resemble windmills, scorpions, and manta rays and those that have application potentials in tunable inductors and vibrational microsystems.

Characterization of magnetomechanical properties in FeGaB thin films

Layered magnetic/piezoelectric heterostructures have drawn a great amount of interest for their potential use in ultra-sensitive magnetoelectric (ME) sensors, ME antennas, voltage tunable inductors, magnetic tunable resonators, etc. It is critically important to characterize the saturation magnetostriction, piezomagnetic coefficient, ΔE effect, and magnetomechanical coupling factor of magnetic thin films, which determine the performance of these ME devices. In this work, a sensitive system has been developed to measure these magnetomechanical properties, on which several different magnetostrictive thin films on the silicon substrate cantilever were characterized. A 0.015 ppm limit of detection of the magnetostriction tester and a frequency resolution of 0.01 Hz of the ΔE tester have been achieved. After magnetic anneal treatment, a record high piezomagnetic coefficient of 12 ppm/Oe, a giant magnetic field induced Young's modulus change of 153 GPa, and a high effective magnetomechanical coupling factor of 0.84 have been measured in FeGaB thin films.

Analyses of mechanically-assembled 3D spiral mesostructures with applications as tunable inductors

Mechanically-guided assembly allows the formation of 3D spiral-shaped inductors through controlled buckling, which could provide an increased quality ( Q ) factor and broadened working angle in near field communication, as compared to the planar design. An understanding of the microstructure-property relationship is essential in the design optimization of the assembly process. This work presents a theoretical model to analyze the deformations during the assembly of the 3D spiral-shaped mesostructure from a bilayer precursor that consists of a supporting ribbon and a 2D coil on its top. As validated by both the experiments and finite element analyses (FEA), this mechanics model allows accurate predictions of the assembled 3D configurations. In combination of electromagnetic simulations, we investigated the effects of various key design parameters on the final 3D configuration and the Q factor when operated as an inductor. The results suggest a significant role of the gravity effect on the assembled spiral configuration, especially for flexible coil designs with relative small cross-sectional areas or long wires. This study can serve as a reference for the design of spiral-shaped 3D inductors in different device applications.

Colossal tunability in high frequency magnetoelectric voltage tunable inductors

The electrical modulation of magnetization through the magnetoelectric effect provides a great opportunity for developing a new generation of tunable electrical components. Magnetoelectric voltage tunable inductors (VTIs) are designed to maximize the electric field control of permeability. In order to meet the need for power electronics, VTIs operating at high frequency with large tunability and low loss are required. Here we demonstrate magnetoelectric VTIs that exhibit remarkable high inductance tunability of over 750% up to 10 MHz, completely covering the frequency range of state-of-the-art power electronics. This breakthrough is achieved based on a concept of magnetocrystalline anisotropy (MCA) cancellation, predicted in a solid solution of nickel ferrite and cobalt ferrite through first-principles calculations. Phase field model simulations are employed to observe the domain-level strain-mediated coupling between magnetization and polarization. The model reveals small MCA facilitates the magnetic domain rotation, resulting in larger permeability sensitivity and inductance tunability.

Integrated magnetoelectric devices: Filters, pico-Tesla magnetometers, and ultracompact acoustic antennas

Abstract

Integrated ferroics for sensing, power, RF, and µ-wave electronics

Abstract

RF and microwave reconfigurable bandpass filter design using optimized active inductor circuit

In this article, a design methodology of an active bandpass filter (BPF) using tunable active inductor (TAI) achieving wide frequency contiguous tuning range (FTR) is presented. The tunable BPF is realized with a differential TAI (DTAI) employing two-reconfiguration mechanisms one for coarse-tuning using a controllable current source while the fine-tuning is performed through a variable feedback resistance. The center frequency tuning is performed through the variation of the DTAI control voltages. A cross-coupled pair based negative resistance technique is also applied to compensate the resistive losses of equivalent RLC resonator. The filter performances are significantly improved using several optimization techniques such as voltage scaling and multigate finger techniques. The proposed BPF is simulated using 0.13 μm CMOS technology. The filter achieves an insertion loss (IL) of 26.62-33.45 dB over the tuning range 1.16-3.27 GHz with a relative bandwidth of 1.3%-3.4%. The noise figure and input 1-dB compression point at 1.84 GHz are 14.93 dB and 2.72 dBm, respectively. The designed RF filter consumes an average power of 5 mW at 1 V supply voltage.

A 60-GHz Transmission Line Phase Shifter Using Varactors and Tunable Inductors in 65-nm CMOS Technology

This paper describes a 60-GHz artificial transmission line phase shifter designed in 65-nm CMOS technology. To increase the phase shift range and preserve the matching over the entire phase shift range, the fixed series inductors in the standard line cell are substituted by tunable inductors. The required tunable inductors are constructed using a transformer with the transformer secondary loaded by a varactor. To verify the operation principle, the phase shifters, including one-, two- and three-cell, are manufactured. The experimental phase shift range is 45° for one-cell, 92° for two-cell, and 133° for three-cell line shifters. These figures are nearly 80% larger than the corresponding phase shifts in the lines consisting of cells with fixed inductors. The input/output return loss is less than 10 dB for all cases over the entire phase shift range. The average insertion loss is 3.2 dB for one-cell, 5.6 dB for two-cell, and 7.8 dB for three-cell transmission line phase shifters. The proposed continuous phase shifter achieves the highest phase shift range per area among the millimeter-wave transmission line and switch-type phase shifters reported to date.

Bidirectional tunable ferrite-piezoelectric trilayer magnetoelectric inductors

A tunable magnetoelectric inductor composed of a symmetrical trilayer of Ga-doped NiZn ferrite and PZT in a solenoid has been developed. Under the influence of external electric/magnetic fields, the permeability variation arising from magnetostriction and piezoelectric strain in the composite results in a bidirectional tuning of the inductance L with a maximum tunability of 571% at a lower magnetic field. The largest variation in L occurs for frequencies centered around longitudinal acoustic resonance. The dual and large tunability of L is of importance for applications in compact and power-efficient integrated circuits.

Synthetic control systems for high performance gene expression in mammalian cells.

Tunable induction of gene expression is an essential tool in biology and biotechnology. In spite of that, current induction systems often exhibit unpredictable behavior and performance shortcomings, including high sensitivity to transactivator dosage and plasmid take-up variation, and excessive consumption of cellular resources. To mitigate these limitations, we introduce here a novel family of gene expression control systems of varying complexity with significantly enhanced performance. These include: (i) an incoherent feedforward circuit that exhibits output tunability and robustness to plasmid take-up variation; (ii) a negative feedback circuit that reduces burden and provides robustness to transactivator dosage variability; and (iii) a new hybrid circuit integrating negative feedback and incoherent feedforward that combines the benefits of both. As with endogenous circuits, the complexity of our genetic controllers is not gratuitous, but is the necessary outcome of more stringent performance requirements. We demonstrate the benefits of these controllers in two applications. In a culture of CHO cells for protein manufacturing, the circuits result in up to a 2.6-fold yield improvement over a standard system. In human-induced pluripotent stem cells they enable precisely regulated expression of an otherwise poorly tolerated gene of interest, resulting in a significant increase in the viability of the transfected cells.

Note: Development of a triple resonance pulse transformer based on magnetic core transformer.

In this paper, a triple resonance pulse transformer based on a magnetic core transformer is developed, which uses the first peak of the output voltage to charge the load capacitor. A compact magnetic core pulse transformer is developed, which uses an innovative bi-conical specific geometry. Based on this magnetic core pulse transformer, the triple resonance circuit is built by adding a tuning capacitor and a tuning inductor between this transformer and a pulse forming line (PFL). The tuning capacitor is designed to be an irregular coaxial capacitor with a capacitance of 70 pF and the tuning inductor is made as a single-layer air core cylindrical inductor. The experimental results indicate that the peak output voltage of the triple resonance pulse transformer is about 530 kV and the rise time is about 790 ns. The peak voltage across PFL is 1.6 times the peak voltage across the magnetic core transformer. It is feasible to develop a magnetic core pulse transformer into a triple resonance pulse transformer.

Optimal piezoelectric resistive–inductive shunt damping of plates with residual mode correction

This work concerns vibration suppression of plates and plate-like structures by resonant piezoelectric damping, introduced by resistive–inductive shunts. The performance of this type of shunt damping relies on the precise calibration of the shunt frequency, where an important aspect is the ability to account for the energy spill-over from the non-resonant modes, not taken into account by most available calibration methods. A newly proposed calibration procedure includes this residual mode contribution by a quasi-dynamic modal correction, taking both flexibility and inertia effects of the non-resonant modes into account. In this work, this procedure is implemented in a finite element model combining Kirchhoff plate bending kinematics for the host structure and a plane stress assumption for a pair of bonded piezoceramic patches. The established model is verified by comparison with shunt calibrations from benchmark examples in the literature. As demonstrated by frequency response plots and the obtained damping ratios, the resistive–inductive shunt tuning is influenced by the effect of the non-resonant modes and omission may yield a significant detuning of the shunt circuit. Finally, an alternative method for precise evaluation of the effective (or generalized) electromechanical coupling coefficient is derived from the modal electromechanical equations of motion. This results in a new shunt tuning method, based on the effective electromechanical coupling coefficient obtained by the short- and open-circuit frequencies of the coupled piezo-plate structure.

A Reconfigurable Inductor Based on Vanadium Dioxide Insulator-to-Metal Transition

This letter introduces a reconfigurable planar square-coil-shaped inductor exploiting as the tuning mechanism the insulator-to-metal transition (IMT) of a vanadium dioxide (VO2) switch placed in the interwinding space in an unprecedented manner. The VO2 thin-film bar-shaped switch is electrically connected to provide a temperature-selective current path that effectively short-circuits a part of the inductor coil changing the inductance of the device. The inductor is fabricated on a high-resistivity silicon substrate using a CMOS-compatible 2-D planar low-cost technology (four photolithography steps). The design, optimized to work in the 4–10-GHz range, provides measured inductances at 5 GHz of 2.1 nH at 20 °C and 1.35 nH at 100 °C with good stability in the entire frequency band (4–10 GHz) resulting in a reconfiguration ratio of 55%. The quality factor (Q-factor) at 7 GHz is about 8 at 20 °C (off state) and 3 at 100 °C (on state), outperforming tunable inductors employing VO2 with 2 orders of magnitude higher Q-factor and a smaller footprint. This represents an advancement for the state of the art of 2-D CMOS-compatible inductors in the considered frequency range.

Electromechanical impedance-based damage identification enhancement using bistable and adaptive piezoelectric circuitry

The electromechanical impedance-based damage identification approaches have shown excellent potential in identifying small-sized structural defects, while maintaining simplicity in implementation. The available independent impedance measurement data sets, however, are generally far fewer than the number of required system parameters. As a result, the inverse problem for damage identification is seriously underdetermined, which undermines the reliability of damage prediction since the inverse solution becomes extremely sensitive to even small amount of error in the measurement, especially in practical applications with unavoidable noise and damping influences. This research aims to advance the state of the art by developing a novel approach that (a) enables highly accurate measurement of damage-induced impedance variations against noise and (b) fundamentally improves the underdetermined inverse problem to reliably identify the location and severity of small damages. This new approach utilizes the strongly non-linear bifurcation phenomena in bistable electrical circuits that may exhibit dramatic changes in the response due to small input variations. In this study, an array of bistable circuits is strategically integrated with the structure and piezoelectric transducer so that small damage-induced changes in the piezoelectric impedance can be accurately determined by monitoring whether each circuit exhibits intra- or inter-well responses. This measurement data set is greatly enriched by utilizing an adaptive piezoelectric circuitry with tunable inductor integrated with the monitored structure, which introduces more degrees of freedom into the system. By selectively tuning the inductance values, the dynamic characteristic of the electromechanically coupled system can be altered, thereby one can significantly increase the number of impedance variation measurements for the same damage profile. The enriched data set is utilized to fundamentally improve the underdetermined inverse problem for damage identification. A series of numerical and experimental damage identification studies verify that the proposed methodology can significantly enhance the accuracy and reliability of impedance-based damage identification.

A low power tunable inductor based on active capacitor with negative resistance

A method to provide a low power tunable inductor is presented in which the inductance and its equivalent series resistance can be independently tuned. This equivalent series resistance can be also set to negative or zero value that is corresponding to inductor with ideal quality factor. In this method, a varactor is placed in parallel with a passive inductor and then, an active capacitor is placed in series with them. To this end, a low power Tunable Active Capacitor (TAC) is proposed which is capable of generating tunable capacitor and large negative resistance to compensate the loss of tunable inductor circuit. Also, the power consumption is low because of using a diode-connected transistor. A prototype of the proposed circuit is designed and simulated at 4 GHz. The electromagnetic simulation results show the inductance tuning range of 0.48–2.3nH with zero or even negative equivalent series resistance is obtained while the power dissipation is less than 3 mW. Moreover, noise analysis shows that higher inductance translates to lower noise while there is a weak correlation between noise and quality factor of the obtained inductances.

A Widely Tunable Bandpass CMOS Filter Based on a Low-Voltage Active Inductor

A Chebyshev bandpass filter for digital TV (DTV) tuner ICs, as an RF tracking filter, based on a low-voltage tunable active inductor (TAI) is presented. The new filter has a tuning range of 200–800[Formula: see text]MHz. Independent tuning of the inductance and central frequency of the filter are very important in this wide frequency span. Adjusting the inductance for tuning of the filter should not vary its quality factor and consequently performance of the filter. Use of a feedback resistor in the active inductor makes the inductance and quality factor tuning-independent. Moreover, the feedback resistor increases the quality factor of the active inductor. Biasing the bulk terminals of the devices to a positive voltage, we achieve low threshold devices and consequently low voltage TAI. The proposed filter has IIP3 and noise figure of [Formula: see text]0.8 to 9.5[Formula: see text]dBm and 19.1 to 20.9[Formula: see text]dB, respectively. Besides, the power consumption varies from 9.6 to 25.5[Formula: see text]mW in the tuning range of 200–800[Formula: see text]MHz.

CMOS Active Inductor Based Voltage Controlled Oscillator

<p class="MsoNormal" style="margin-top: 6.0pt; text-align: justify;"><span style="font-size: 9pt;" lang="EN-IN">A Tunable Active Inductor (TAI) based Voltage Controlled Oscillator (VCO) for Radio Frequency (RF) applications ranging from 670 MHz - 1.53 GHz is presented. A design of low phase noise and compact VCO is proposed. In order to lower the phase noise of VCO, its RF output power has been improved. The use of low voltage active in-ductor circuit reduces the power dissipation of VCO. The single ended CMOS active inductors with minimum number of transistors are used to consume less die area of VCO circuit. The low power dissipation of the circuit have high efficiency to generate output RF power. A supply independent variable current source tunes the VCO. The post layout design is simulated in Cadence spectreRF using TSMC 180 nm process libraries. The VCO circuit shows the phase noise variation from -124 to - 126 dBc/Hz and an active area of 0.0049 mm<sup>2</sup>. The VCO core circuit, excluding output buffers, consumes 10 mW at 1.8 V supply voltage.</span></p>

Tunable ohmic environment using Josephson junction chains

We propose a scheme to implement a tunable, wide frequency-band dissipative environment using a double chain of Josephson junctions. The two parallel chains consist of identical SQUIDs, with magnetic-flux tunable inductance, coupled to each other at each node via a capacitance much larger than the junction capacitance. Thanks to this capacitive coupling, the system sustains electromagnetic modes with a wide frequency dispersion. The internal quality factor of the modes is maintained as high as possible, and the damping is introduced by a uniform coupling of the modes to a transmission line, itself connected to an amplification and readout circuit. For sufficiently long chains, containing several thousands of junctions, the resulting admittance is a smooth function versus frequency in the microwave domain, and its effective dissipation can be continuously monitored by recording the emitted radiation in the transmission line. We show that by varying in-situ the SQUIDs' inductance, the double chain can operate as tunable ohmic resistor in a frequency band spanning up to one GHz, with a resistance that can be swept through values comparable to the resistance quantum R_q = (h/4e^2) ~ 6.5 k{\Omega}. We argue that the circuit complexity is within reach using current Josephson junction technology.

TIME—Tunable Inductors Using MEmristors

Memristors have proven to be an attractive feature for memory, logic-in-memory, and neuromorphic computing. Recently, radio-frequency memristive switches (RFMSs) have exhibited promising high-frequency performance, opening the possibility of their use in radio-frequency integrated circuit applications. In this paper, we present two novel topologies of Tunable Inductors using MEmristors, the memristive–via the switched tunable inductor and the multi-layer stacked inductor switched by an RFMS single-pole double-throw. The two inductor topologies are fully passive and are tuned by electrochemical metallization memristors. Memristive devices improve the performance of tunable inductors, as they provide low-area overhead, low-energy switching, and non-volatility, resulting in more compact and energy-efficient devices. The topologies are implemented and simulated in a momentum 3-D planar electromagnetic simulator. Simulation results show a maximum tunability of 296%, a quality factor of 18 at 5 GHz, and self-resonant frequency above 8.4 GHz.