Tunable Inductor Research Articles

Patterned Permalloy and Barium Strontium Titanate Thin Film Enabled Tunable Slow Wave Elements for Compact Multi-Band RF Applications

We have designed and proposed tunable slow wave RF elements enabled with patterned Permalloy (Py) and barium strontium titanate (BST) nano thin films. A slow wave element structure with discontinuous signal width is designed and implemented in an IBM 45 nm CMOS technology. Effects of pitch length and signal width ratio on slow wave effects are discussed. Inductance variations of Py embedded transmission lines for different dc levels are studied, and capacitance variations of BST thin film are investigated and measured. Results show that the designed slow wave element can have both 2:1 inductance and capacitance tuning ratio with 50 mA dc current and 5 V voltage applied respectively. Multi-band, multi-functionality RF components with miniaturized size can be achieved using this design.

An eclectic approach to design tunable amplifiers

Broadband amplifiers that can accommodate commercial communication standards such as GSM, UMTS, Wi-Fi, and Wi-Max are extremely important for radio equipment manufacturers. To achieve this coverage, the amplifier should provide high gain and efficiency over a band from 800 to 5200 MHz. Although there are transistor devices that have cut-off frequencies well over these frequencies, amplifiers covering such a broad-bandwidth are difficult to design due to the requirement of broadband matching networks. In this work, design of broadband tunable matching networks is investigated using Real Frequency Direct Computational Technique (RF-DCT). In order to be able to work on sample structures, impedance transforming filters are chosen and a broadband tunable matching network has been designed. Implementation of tunable inductors is investigated and the performance of a tunable matching network using tunable inductors and capacitors is demonstrated. Eventually a broadband frequency tunable amplifier has been designed using the tunable inductor concept. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2013.

Analysis and Design of Stacked-FET Millimeter-Wave Power Amplifiers

Stacked field-effect transistor (FET) CMOS millimeter-wave power amplfiers (PAs) are studied with a focus on design of appropriate complex impedances between the transistors. The stacking of multiple FETs allows increasing the supply voltage, which, in turn, allows higher output power and a broader bandwidth output matching network. Different matching techniques for the intermediate nodes are analyzed and used in two-, three-, and four-stack single-stage $Q$ -band CMOS PAs. A four-stack amplifier design achieves a saturated output power greater than 21 dBm while achieving a maximum power-added efficiency (PAE) greater than 20% from 38 to 47 GHz. The effectiveness of an inductive tuning technique is demonstrated in measurement, improving the PAE from 26% to 32% in a two-stack PA design. The input and output matching networks are designed using on-chip shielded coplanar waveguide transmission lines, as well as metal finger capacitors. The amplifiers were implemented in a 45-nm CMOS silicon-on-insulator process. Each of the amplifiers occupies an area of 600 $\mu$ m $\,\times\,$ 500 $\mu$ m including pads.

Wide tuning-range CMOS VCO based on a tunable active inductor

In this paper, a wide tuning-range CMOS voltage-controlled oscillator (VCO) with high output power using an active inductor circuit is presented. In this VCO design, the coarse frequency is achieved by tuning the integrated active inductor. The circuit has been simulated using a 0.18-µm CMOS fabrication process and presents output frequency range from 100 MHz to 2.5 GHz, resulting in a tuning range of 96%. The phase noise is –85 dBc/Hz at a 1 MHz frequency offset. The output power is from –3 dBm at 2.55 GHz to +14 dBm at 167 MHz. The active inductor power dissipation is 6.5 mW and the total power consumption is 16.27 mW when operating on a 1.8 V supply voltage. By comparing this active inductor architecture VCO with general VCO topology, the result shows that this topology, which employs the proposed active inductor, produces a better performance.

HIGH QUALITY FACTOR L-BAND ACTIVE INDUCTOR-BASED BAND-PASS FILTERS

In this letter, a tunable high-Q active inductor with high dynamic range is presented. The equivalent inductance and resistance values can be tunable in a wide frequency range by changing the compensating network components values; outside the operating frequency band, the equivalent resistance increases, improving signal rejection for band-pass filter applications. A second-order active band-pass filter with a central frequency of 2100 MHz using the high-Q active inductance has been fabricated and tested.

Inductive Tuning of Fano-Resonant Metasurfaces Using Plasmonic Response of Graphene in the Mid-Infrared

Graphene is widely known for its anomalously strong broadband optical absorptivity of 2.3% that enables seeing its single-atom layer with the naked eye. However, in the mid-infrared part of the spectrum graphene represents a quintessential lossless zero-volume plasmonic material. We experimentally demonstrate that, when integrated with Fano-resonant plasmonic metasurfaces, single-layer graphene (SLG) can be used to tune their mid-infrared optical response. SLG's plasmonic response is shown to induce large blue shifts of the metasurface's resonance without reducing its spectral sharpness. This effect is explained by a generalized perturbation theory of SLG-metamaterial interaction that accounts for two unique properties of the SLG that set it apart from all other plasmonic materials: its anisotropic response and zero volume. These results pave the way to using gated SLG as a platform for dynamical spectral tuning of infrared metamaterials and metasurfaces.

Low-loss tunable metamaterials using superconducting circuits with Josephson junctions

We report on experiments with superconducting metamaterials containing Josephson junctions. In these structures, split-ring resonators used in conventional metamaterials are replaced by superconducting loops that are interrupted by Josephson junctions, so called rf-SQUIDs. Like the split-ring resonators, these elements can be seen as LC-resonators that couple to the magnetic field. The advantage of superconducting thin-film metamaterials is that, due to the tunable intrinsic inductance of the Josephson junction, the resonance frequency of the rf-SQUID can be changed by applying an external dc magnetic field. We present experimental results that demonstrate the tunability of the resonance frequency of these devices.

Tuning Promoter Strengths for Improved Synthesis and Function of Electron Conduits in Escherichia coli

Introduction of the electron transfer complex MtrCAB from Shewanella oneidensis MR-1 into a heterologous host provides a modular and molecularly defined route for electrons to be transferred to an extracellular inorganic solid. However, an Escherichia coli strain expressing this pathway displayed limited control of MtrCAB expression and impaired cell growth. To overcome these limitations and to improve heterologous extracellular electron transfer, we used an E. coli host with a more tunable induction system and a panel of constitutive promoters to generate a library of strains that separately transcribe the mtr and cytochrome c maturation (ccm) operons over 3 orders of magnitude. From this library, we identified strains that show 2.2 times higher levels of MtrC and MtrA and that have improved cell growth. We find that a ~300-fold decrease in the efficiency of MtrC and MtrA synthesis with increasing mtr promoter activity critically limits the maximum expression level of MtrC and MtrA. We also tested the extracellular electron transfer capabilities of a subset of the strains using a three-electrode microbial electrochemical system. Interestingly, the strain with improved cell growth and fewer morphological changes generated the largest maximal current per cfu, rather than the strain with more MtrC and MtrA. This strain also showed ~30-fold greater maximal current per cfu than its ccm-only control strain. Thus, the conditions for optimal MtrCAB expression and anode reduction are distinct, and minimal perturbations to cell morphology are correlated with improved extracellular electron transfer in E. coli.

Design of VCO with a Differential Tunable Active Inductor

This paper presents a wide tuning rang CMOS voltage control oscillator (VCO) suitable for radio frequency operation. The oscillator based upon the classic LC-tuned negative-resistance topology, with a novel low voltage, high performance active inductor. In the proposed circuits' structure, the coarse frequency tuning is provided by the tunable active inductor, while the fine tuning is controlled by varactor. Using a 0.18µm CMOS process, complete pattern VCOs are designed in ADS. The output frequency is 5.5GHz. The measured phase noise in 1-MHz offset is -81dBc. The non existence of passive components causes VCO to have the smaller chip area than the circuit with passive inductors.

Current-mode phase-locked loop with constant-Q active inductor CCO and active transformer loop filter

This paper presents a current-mode phase-locked loop (PLL) with a constant-Q CMOS active inductor current-controlled oscillator (CCO) and a CMOS current-mode active-transformer loop filter. The constant-Q active inductor provides a large and swing-independent quality factor such that the phase noise of the CCO utilizing the constant-Q active inductor is comparable to that of CCO with spiral inductors. The current-mode active-transformer loop filter offers the advantage of a large and tunable inductance and low silicon consumption such that the loop bandwidth of the PLL can be made small and tunable. The PLL was designed in TSMC-0.18 μm 6-metal 1.8V CMOS technology and analyzed using SpectreRF from Cadence Design Systems with BSIM3v3 device models. The phase noise of the PLL was analyzed using Cadence's Verilog-AMS behavioral modeling. The phase noise of the CCO with the constant-Q active inductor is ?123.1 dBc/Hz at 1 MHz frequency offset, over 10 dB better as compared with that of the CCO with conventional active inductors, and is only a few dB higher than that of the CCO with spiral inductors. The phase noise of the PLL with an active-transformer loop filter and a constant-Q CCO is ?116 dBc/Hz at 1 MHz frequency offset, nearly 20 dB lower than that of the PLL with the same active-transformer loop filter and a conventional active-inductor CCO. The lock time, power consumption, and phase noise of the PLL are 60 ns, 34 mW, and ?116 dBc/Hz at 1 MHz frequency offset, respectively. The total silicon consumption of the PLL excluding bond pads is 0.013 mm2.

25 An MRI Coil Dual-Tuned by RF Shielding for In-Vivo Detection of Fluorine Labelled Stem-Cells in a Rodent Model of Acute Myocardial Infarction

Stem-cell therapy holds great promise for treatment of disease. However, optimal stem-cell type, number, route, timing of administration have yet to be quantitatively determined. Non-invasive methods of monitoring cell retention...

A Reconfigurable Low-Noise Amplifier Using a Tunable Active Inductor for Multistandard Receivers

A reconfigurable low-noise amplifier (LNA) based on a high-value active inductor (AI) is presented in this paper. Instead of using a passive on-chip inductor, a high-value on-chip inductor with a wide tuning range is used in this circuit and results in a decrease in the physical silicon area when compared to a passive inductor-based implementation. The LNA is a common source cascade amplifier with RC feedback. A tunable active inductor is used as the amplifier output load, and for input and output impedance matching, a source follower with an RC network is used to provide a 50 Ω impedance. The amplifier circuit has been designed in 0.18 µm CMOS process and simulated using the Cadence Spectra circuit simulator. The simulation results show a reconfigurable frequency from 0.8 to 2.5 GHz, and tuning of the frequency band is achieved by using a CMOS voltage controlled variable resistor. For a selected 1.5 GHz frequency band, simulation results show S 21 (Gain) of 22 dB, S 11 of −18 dB, S 22 of −16 dB, NF of 3.02 dB, and a minimum NF (NFmin) of 1.7 dB. Power dissipation is 19.6 mW using a 1.8 V dc power supply. The total LNA physical silicon area is (200×150) µm2.

Ultra-low power electrically reconfigurable magnetoelectric microwave devices

We present an electrical tunable spiral inductor design and simulation results. By integrating (011) oriented single crystal ferroelectric substrate [Pb(Mg1/3Nb2/3)O3](1−x)-[PbTiO3]x (PMN-PT, x ≈ 0.32) with tunable and switchable remanent strain property, the tunability of such magnetoelectric microwave inductor can retain after releasing the electric actuation, i.e., electrically reconfigurable. A series of reconfigurable passive magnetoelectric microwave devices based on this concept are proposed and discussed. Those electrically reconfigurable magnetoelectric microwave devices have the advantage of low power consumption and fast and wide tunability, which can be potentially used for many applications.

High-Performance Micromachined Inductors Tunable by Lead Zirconate Titanate Actuators

This letter documents the design, microfabrication, and testing of integrated and continuously tuned radiofrequency copper (Cu) inductors with low-power large-throw lead-zirconate-titanate (PZT) actuators. The devices, with inductances in the 3-10-nil range, achieved high-quality factors, Q >; 10 (1-6 Gilz range), and tuning ratios as high as 2.6:1 at 20-V actuation with nanowatt-power consumption. This was enabled by the monolithic integration of three electroplated Cu layers (~10 μm per layer) and PZT microelectromechanical system actuators. Two tunable inductor design types, positively and negatively coupled designs, and the tradeoff between tuning ratio and inductor Q are considered.

A 1.9 GHz CMOS Power Amplifier With Embedded Linearizer to Compensate AM-PM Distortion

A series combining transformer(SCT)-based, watt-level 1.9 GHz linear CMOS power amplifier with an on-chip linearizer is demonstrated. Proposed compact, predistortion-based linearizer is embedded in the two-stage PA to compensate AM-PM distortion of the cascode power stages, and improve ACLR of 3GPP WCDMA uplink signal by 2.6 dB at 28.0 dBm output power. The designed interstage power distributor with one tuning inductor contributes to low-loss power supply for the driver stage and high common-mode stability of the whole PA. Moreover, a newly developed PVT variation- tolerant cascode biasing circuit guarantees highly accurate bias voltages in a wide supply voltage range from 2.5 V to 3.6 V. The test chip demonstrates maximum output power of 28.3 dBm at 1.95 GHz, satisfying 3GPP WCDMA spectrum mask with die area of 5.4 mm2.

A Dual-Resonant Mode 10/22-GHz VCO With a Novel Inductive Switching Approach

This paper presents a novel dual-band voltage-controlled oscillator (VCO) in a standard 0.18-μm CMOS technology. With special design in the LC tank, the circuit exhibits two oscillation modes in different frequency bands. The frequency band selection is achieved by a switched coupled inductor with the tunable inductance and quality factor. This VCO can operate in a 10-GHz band with 7.6% tuning range and a 22-GHz band with 8% tuning range, while the core circuit draws a dc current of 8.44 mA from a 1.8-V supply voltage. The figures-of-merit at 10- and 22-GHz bands are - 184.63 and - 181.81 dBc/Hz, respectively. These performances are comparable with state-of-the-art dual-band LC-VCOs.

Planar Solenoidal Inductor in Radio Frequency Micro-Electro-Mechanical Systems Technology for Variable Inductor with Wide Tunable Range and High Quality Factor

A planar solenoidal inductor for the realization of a variable inductor with a wide tunable range and a high quality factor (Q-factor) is proposed in this work. Prototype inductors are designed and fabricated using a two-metal micro-electro-mechanical systems (MEMS) process to demonstrate the potential use of the tunability of the inductance and the Q-factor. Inductance tuning from 1 to 3.3 nH was achieved and the tunability obtained was as high as 230% at 2 GHz. A Q-factor of more than 20 was observed in the frequency range of 2.5 to 6 GHz.

A simple CMOS-based inductor simulator and frequency performance improvement techniques

In this paper, a new CMOS grounded positive tunable inductor simulator based on using two simple CMOS transconductors and an inverting amplifier is presented. The introduced inductor simulator uses a grounded capacitor; accordingly, it is suitable for integrated circuit (IC) fabrication. In addition a CMOS circuit for realizing negative tunable resistor which can be used for parasitic cancellation in inductor simulators and consequently enhancing their frequency performances is developed. A novel method for providing high-frequency performance improvement of simulated inductors is also introduced. Simulation and experimental results are given to demonstrate the performance of the developed inductor simulator and validity of the proposed frequency performance improvement method.

Active Inductor based Low Noise Amplifier for Ultra Wide Band Receiver

In this paper a three stage Active Inductor (AI) based Low Noise Amplifier (LNA) for Ultra Wide Band (UWB) receiver is presented. A fully differential topology has been adopted in order to improve the circuit robustness against unwanted common mode signals. T-coil peaking is used to enhance the bandwidth over the entire Ultra Wide Band frequency range. Active inductor is employed because of its low area, tunable inductance and high quality factor. Simultaneous Noise and Impedance Matching (SNIM) is employed to reduce the noise figure of the design. Resistive source degeneration has been implemented to improve the linearity of the circuit. The proposed LNA is designed using 90nm CMOS technology. The proposed LNA achieves power gain (S21) greater than 12dB throughout the UWB spectrum providing a bandwidth of 4 – 11 GHz. The input matching (S11) and output matching (S22) are kept well below -10 dB and – 8dB respectively, while the reverse isolation (S12) is less than -43 dB providing a linearity of -6.9 dBm. Upon adoption of SNIM the Noise Figure falls in the range 4.4 8.2 dB. General Terms Full Custom Design, RF VLSI

A tunable CMOS Wilkinson power divider using active inductors

This paper presents the design and implementation of a tunable CMOS Wilkinson power divider using active inductors. Compared to a conventional active inductor topology, the proposed active inductor features higher inductance tuning range, higher self-resonant frequency, and lower power consumption by introducing two additional transistors. Benefitting from the superior inductor, the low-loss Wilkinson power divider is practical while maintaining a wide tuning range. The design consuming 10.2mW demonstrates an insertion loss of 0.67dB, a return loss of 27dB, and an isolation of 22.6dB at 8GHz. Moreover, the tuning range of the circuit is between 5.8GHz and 10.4GHz, rendering a 4.6GHz bandwidth. The active chip size of the lumped design is merely 0.25mm×0.15mm.