Lumped-element Circuit Research Articles

New designed helical resonator to improve measurement accuracy of magic radio frequency

Based upon the new designed helical resonator, the resonant radio frequency (RF) for trapping ions can be consecutively adjusted in a large range (about 12 MHz to 29 MHz) with high Q-factors (above 300). We analyze the helical resonator with a lumped element circuit model and find that the theoretical results fit well with the experimental data. With our resonator system, the resonant frequency near magic RF frequency (where the scalar Stark shift and the second-order Doppler shift due to excess micromotion cancel each other) can be continuously changed at kHz level. For 88Sr+ ion, compared to earlier results, the measurement accuracy of magic RF frequency can be improved by an order of magnitude upon rough calculation, and therefore the net micromotion frequency shifts can be further reduced. Also, the differential static scalar polarizability Δα 0 of clock transition can be experimentally measured more accurately.

Bandpass filters based on integrated aperture‐ and gap‐coupled discontinuities

An electromagnetic coupling mechanism is discussed for distributed-element aperture- and gap-coupled discontinuities based on rigorous lumped-element equivalent circuit analysis. The two discontinuities are analysed in terms of their transmission poles and transmission zeros for the selectivity enhancement of microwave and or millimetre-wave components. The integration of these two discontinuities is put forward for bandpass filter design. A frequency-dependent lumped-element equivalent circuit is employed to study the behaviour of the two distributed-element discontinuities in the transverse direction. Bandpass filters are characterised based on the dual aperture- and gap-coupled discontinuities integrated within substrate integrated waveguide structures. It is shown that multiple transmission zeros close to transmission poles are realised due to the magnetic and electric field cancelation in the gap-coupled discontinuity, while the aperture-coupled discontinuity contributes to a resonator with a higher quality factor. The integration of both aperture- and gap-coupled discontinuities shows the priority of this kind of microwave resonator in terms of selectivity, size, and upper stopband in comparison with the conventional aperture-coupled one.

RF performances at cryogenic temperature of inductors integrated in a FDSOI technology

This paper investigates the RF performances of octagonal inductors integrated in a Fully Depleted Silicon On Insulator (FD-SOI) technology at cryogenic temperature. The RF performances characterization of passive and active components is a first necessary step towards the design of RF circuits optimized for cryogenic CMOS applications. Among passive components, inductors are key to design low noise amplifier needed for instance in qubits read-out circuit. First, the experimental set-up and the experimental protocol is presented in detail. Then inductance with 0.5nH to 4nH values are characterized in frequency from room temperature down to 4.2 K and modelled by a lumped elements circuit. We used a simple RLC circuit to describe the self-resonance behaviour. A calculation is proposed for the inductance and the capacitance, whereas the resistance is extracted by DC measurements. This circuit description is improved by including coil proximity and skin effects. We observed that the quality factor is improved by a factor of two at low temperature, thanks to the metal resistivity decreases, in qualitative agreement with DC measurements. We also discussed the limits of the proposed model.

Equivalent Circuit Approximation to the Connector-Line Transition at High Frequencies using Two Microstrip Lines and Data Fitting

This article presents a method of obtaining an equivalent lumped element circuit to model the electrical connector-line transitions in the ultra-high frequency (UHF) band. First, the scattering matrices of two microstrip transmission lines that are otherwise identical but have the physical lengths of dd and 2d2⁢d are measured. Next, the theoretical model of the lines cascaded with the connector-line transitions modeled as lumped element circuits is established. The selection of the line lengths to be dd and 2d2⁢d results in an over determined system of equations that links the circuit component values to the two-port network parameters of the cascaded system. Finally, the least-squares data fitting procedure yields the best-fit component values. The results show that in our tested scenario, 3-component reactive circuit models well the transitions. Compared with the previous methods, the proposed approach does not require knowledge of the dielectric properties of the substrate of the measured transmission lines. This property integrates the method with our previous work on estimating a microstrip line substrate’s relative permittivity and loss tangent. The obtained transition circuit model is also validated through the testing of two quarter-wave transformers. The lines and transformers are implemented on a textile substrate to highlight the method’s applicability to wearable textile-based electronics.

A W-Band Compact Substrate Integrated Waveguide Bandpass Filter With Defected Ground Structure in CMOS Technology

This brief proposes the first on-chip bandpass filter (BPF) based on substrate integrated waveguide (SIW) for W-band applications. Slot-loaded, folded ridge and quarter mode technology is used to reduce the cavity size. The coupling characteristic of two folded ridged quarter mode substrate integrated waveguide (QMSIW) cavities implemented in CMOS technology is investigated. A simplified equivalent lumped-element circuit model of the proposed wide-band BPF approach is provided and applied to study the coupling characteristic of slot-loaded folded ridged QMSIW cavity. Then, a novel coupling method using a defected ground structure is proposed to realize a proper coupling intensity for BPF design. Finally, the proposed BPF design is implemented in a commercial complementary metal-oxide-semiconductor (CMOS) technology, fabricated, and measured. The active size of the proposed cavity resonator is only 405 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}\,\,\times185\,\,\mu \text{m}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.22{\lambda }_{\mathrm{ g}} \times 0.1 \lambda _{\mathrm {g}}$ </tex-math></inline-formula> ), and the measured insertion loss ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\vert|\text{S}_{21}~\vert|$ </tex-math></inline-formula> ) is 3.15 dB with a central frequency of 85.5 GHz.

A tunable bandpass filter with extended passband bandwitdh

AbstractAn Nth-order tunable bandpass filter (BPF) structure with extended passband bandwidth has been proposed in this paper based on the novel tunable resonator and coupling structure. The designed tunable resonator is composed of two coupled lines and one varactor diode, while the presented tunable coupling structure is constructed by two cascaded transmission lines and one short-circuited varactor diode. Moreover, the even-(odd-) method and lumped-element equivalent circuit are employed to analyze the operating mechanisms of the designed Nth-order tunable BPF. Specifically, the frequency tuning range is determined by the characteristic impedance and electrical length of coupled line when the varactor diode is within the fixed tuning range. Then, the design procedure for the Nth-order tunable BPFs is proposed. To demonstrate the presented idea, the second- and third-order fully tunable BPFs have been designed and simulated. Finally, a second-order tunable BPF with the compact size of 0.03λg × 0.13λg has been fabricated and measured, and the measured center frequencies are ranging from 0.91 to 1.46 GHz with the passband bandwidths wider than 11.2%.

Power- and Spatial-Dependent Characterization of Reflection and Transmission Electric Parameters of an Argon Microwave Plasma

In this article, the power- and spatial-dependent macroscopic electrical transmission and reflection properties of an argon microwave plasma are analyzed. A custom two-port coaxial prototype is built with a variable spatial gap between two electrodes. All measurements are based on the extension of the large-signal scattering parameter (Hot-S) measuring environment and are proof-of-concept for the determination of plasma properties without an external probe. The coaxial topology of the prototype has a fixed reference impedance so that the reference planes can be located at the tip of both electrodes. An equivalent lumped element circuit valid over a wide bandwidth is investigated to simulate the linear macroscopic electromagnetic reflection and transmission properties of the plasma. A series-resonance circuit is chosen since its representation is capable of covering the measurements from 10 to 40 W of input power and gaps from 1 to 3 mm. With this circuit, a continuous relationship between the impedance, power, and the spatial dimensions of the plasma is found.

Phenomenological Circuit Modeling of Ferroelectric-Driven Bulk Acoustic Wave Resonators

A nonlinear circuit model has been developed to model electrostriction in thin-film ferroelectric bulk acoustic wave (BAW) resonators. This new model is based on nonlinear coupling relations among strain, stress, electric field, and polarization, derived from the Landau–Devonshire theory. The coupling relations and the mechanical vibrations are then represented as lumped circuit elements using an improved approximation procedure along with an enhanced model for dielectric loss. The response from the simulation is compared with the measurement results obtained for a barium strontium titanate (BST) thin-film bulk acoustic resonator (FBAR) at different dc bias levels. The improved approximation procedure enables one to achieve accurate simulation results with reduced circuit model complexity.

Full-Wave Methodology to Compute the Spontaneous Emission Rate of a Transmon Qubit

The spontaneous emission rate (SER) is an important figure of merit for any quantum bit (qubit), as it can play a significant role in the control and decoherence of the qubit. As a result, accurately characterizing the SER for practical devices is an important step in the design of quantum information processing devices. Here, we specifically focus on the experimentally popular platform of a transmon qubit, which is a kind of superconducting circuit qubit. Despite the importance of understanding the SER of these qubits, it is often determined using approximate circuit models or is inferred from measurements on a fabricated device. To improve the accuracy of predictions in the design process, it is better to use full-wave numerical methods that can make a minimal number of approximations in the description of practical systems. In this work, we show how this can be done with a recently developed field-based description of transmon qubits coupled to an electromagnetic environment. We validate our model by computing the SER for devices similar to those found in the literature that have been well-characterized experimentally. We further cross-validate our results by comparing them to simplified lumped element circuit and transmission line models as appropriate.

Design of Chebyshev Bandpass Waveguide Filter for E-band Based on CSRR Metamaterial

A new design of bandpass waveguide filter with Chebyshev response which operates in the E-band for downlink channel [71 GHz-76 GHz] at 73.5 GHz center frequency. The new design used a complementary split ring resonators (CSRRs) upper and lower rings that are placed on the same transverse plane. A simple model of lumped elements circuit (RLC) model is shown.

Broadband Bandpass Filter for UWB Networks with Multiple In-Band Transmission Zeros

Proposed in this manuscript is a broadband bandpass filter (BPF) with dual in-band transmission zeros (TZs) and elongated stopband for application in ultra-wideband (UWB) networks. The basic structure is developed on the principle of broadside coupling of microstrip-to-coplanar waveguide (CPW). Semi-elliptical microstrips on the top are arranged in back-to-back manner and coupled to the open circuited CPW in the ground. The basic BPF is of 3rd order with good insertion/return loss. To this basic BPF structure multiple defected ground structures (DGS) in the shape of complimentary split ring resonator (CSRR) are appended to place dual Tzs within the passband and later dumbbell-shaped DGS are engraved in the CPW to widen the stopband. Also, an approximate equivalent lumped element circuit model is developed and its frequency characteristics matched against full-wave EM simulation. The proposed dual notched BPF is finally fabricated and is found to occupy a compact area of 13.6 × 6.75 mm2.

Exploiting Parasitic Capacitances in 3-D Inductors to Design RF CMOS Quasi-Elliptic-Type Broad-Band Bandpass Filters

A class of RF broad-band bandpass filter (BPF) with quasi-elliptic-type response in low-cost bulk CMOS technology is reported. It is based on the in-series cascade connection of lowpass and highpass filtering stages with 3-D inductors, whose parasitic capacitances are properly exploited. Specifically, they are used to transform the basic inductor into an LC tank, thus allowing to generate an upper transmission zero (TZ) that increases filtering selectivity and out-of-band power-rejection levels in a spurious-free/extended upper stopband. The layout of a basic third-order BPF cell shaped by four 3-D inductors and its lossless equivalent lumped-element circuit are detailed. By means of this lossless equivalent lumped-element model, its scalability to higher-order BPF designs by in-series cascading various BPF-cell replicas is also demonstrated. For experimental-validation purposes, an on-chip RF CMOS BPF prototype with 11-GHz center frequency and 68.5% 3-dB fractional bandwidth is developed using a 0.13- μm bulk CMOS technology. According to the measured results, it shows an upper stopband with minimum attenuation of 31.7 dB from 22.5 GHz to 67 GHz, alongside with TZs at 3.5 GHz and 22.5 GHz to produce sharp-rejection filtering.

Time-varying materials in the presence of dispersion: plane-wave propagation in a Lorentzian medium with temporal discontinuity

We study the problem of a temporal discontinuity in the permittivity of an unbounded medium with Lorentzian dispersion. More specifically, we tackle the situation in which a monochromatic plane wave forward-traveling in a (generally lossy) Lorentzian-like medium scatters from the temporal interface that results from an instantaneous and homogeneous abrupt temporal change in its plasma frequency (while keeping its resonance frequency constant). In order to achieve momentum preservation across the temporal discontinuity, we show how, unlike in the well-known problem of a nondispersive discontinuity, the second-order nature of the dielectric function now gives rise to two shifted frequencies. As a consequence, whereas in the nondispersive scenario the continuity of the electric displacement D and the magnetic induction B suffices to find the amplitude of the new forward and backward wave, we now need two extra temporal boundary conditions. That is, two forward and two backward plane waves are now instantaneously generated in response to a forward-only plane wave. We also include a transmission-line equivalent with lumped circuit elements that describes the dispersive time-discontinuous scenario under consideration.

Electrical analogs of curved beams and application to piezoelectric network damping

In this paper, the method of electric analog synthesis is applied to design a piezo-electro-mechanical arch able to show the capacity of multimodal damping. An electric-analog circuit is designed by using a finite number of lumped elements representing the equivalent of a curved beam. Spatial and frequency coherence conditions are proven to be verified for the modes to be damped: in fact, lumped-element circuit can damp only a finite number of vibration modes. Analogous boundary conditions are ensured, so that natural frequencies and mode shapes of both the curved beam and the analog circuit are equal. The instance considered here is the vibration mitigation of a piezo-electro-mechanical arch. Having a view towards prototypical applications, all simulations consider values of physically feasible passive circuital elements. It is believed that the present results may represent a step towards the design of multi-physics metamaterials based on micro-structures exploiting the principle of multimodal damping.

Inline Combline Filters of Order N With up to N + 1 Transmission Zeros

In this article, we describe several alternative inline implementations for combline filters with transmission zeros (TZs) located both below and above the passband. A systematic design procedure is also presented using a lumped-element equivalent circuit. Following the design procedure that we propose, up to $N+1$ TZs can be implemented with an inline filter of order $N$ . The generation of the TZs is explained physically in terms of mixed inductive and capacitive couplings. Several filters are also manufactured and tested. Good agreement between the measured and simulated results is demonstrated, thereby fully validating the new filter concepts.

Data-driven modeling of impedance biosensors: a subspace approach

A data-driven scheme for modeling electrical impedance in biosensors is presented by a subspace method working with the singular value decomposition of structured voltage and current data. Contrary to the classical electrical impedance spectroscopy (EIS) methods, our scheme uses simple instrumentation, works in time-domain, provides fast results, and does not require semi-empirical assumptions to retrieve structured models from data. We show how data-driven models exhibit a close relationship with lumped-element circuits, encoding dielectric and conductive properties detected by the sensor in the range from 10 kHz up to 10 MHz. Performance results are shown for calibration networks and two case studies: (i) a buffer solution, and (ii) a biological cell suspension. Finally, the viability of the scheme is discussed when compared with the classical EIS method.

Millimeter-Wave Wide-Band Bandpass Filter in CMOS Technology Using a Two-Layered Highpass-Type Approach With Embedded Upper Stopband

An on-chip millimeter-wave (mm-wave) broad-band bandpass filter (BPF) developed in bulk CMOS technology is reported. It is based on a two-layered implementation in which the circuit structure patterned in the top layer exhibits a highpass-type filtering response, whereas an upper stopband is created by the bottom-layer cell when coupled to the top-layer one to obtain a composite overall quasi-elliptic-type wide-band BPF functionality. The locations of the transmission zeros (TZs), which confer sharp-rejection capabilities to the overall frequency response, can be flexibly adjusted with the values of the capacitors that are employed in both layers. A simplified equivalent lumped-element circuit model of the proposed wide-band BPF approach is provided and applied to multi-stage BPF arrangements for higher-selectivity designs. Furthermore, for practical-demonstration purposes, an on-chip passive-integrated single-stage broad-band BPF prototype on silicon with 34.5-GHz center frequency and 61.2% 3-dB relative bandwidth is designed, manufactured, and characterized.

A chip-sized piezoelectric receiver for low-frequency, near-field wireless power transfer: design, modeling and experimental validation

This work presents the design, modeling and characterization of a chip-sized piezoelectric receiver for low-frequency, near-field wireless power transmission. Utilizing a laser micro-machined titanium suspension, one NdFeB magnet, and two PZT-5A piezo-ceramic patches, the receiver operates at its torsion mode mechanical resonance. Two unimorph piezo-ceramic transducers are designed to maximize the power density of the receiver while maintaining a low mechanical resonant frequency for low-frequency electrodynamic wireless power transmission. An equivalent lumped-element circuit model is used to model the system performance. A prototype device is fabricated, assembled and tested, and the experimental results are compared with the system model. The 0.08 cm3 device generates a maximum of 360 μW average power at 1 cm distance from a transmitter coil operating at 724 Hz and below human head and torso exposure limits. This data corresponds to 4.2 mW cm−3 power density. Overall, this volume-efficient design offers a low-profile and compact footprint for potentially wirelessly charging wearable and bio-implantable devices.

Polarization-independent symmetrical digital metasurface absorber

A metasurface absorber developed using binary-coded unit cells and with the combination of coded unit cells resulted in excellent polarization insensitiveness, symmetrical characteristics, and tunable characteristics. As for binary patterns using the ‘0’ and ‘1’ coded arrangements [00, 01, 10, and 11], ‘1’ position indicates the digital characteristics by high electric and surface current concentration and vice versa for ‘0’. The proposed absorber in this study consisted of a three-layer structure, namely a top metal resonator, an intermediate dielectric layer, and a bottom metallic plane. Structural design, optimization, and result examination of the absorber were performed utilizing the CST microwave studio electromagnetic simulator. Based on the simulated results, absorptance peaks were observed at 11.37 GHz, 15.75 GHz, and 18.76 GHz, whereas the absorptance level were around 97%, 99%, and 94%, respectively. Moreover, the experimented results complied with the simulated results despite slight decreases in absorptance due to cross-polarization effects and free space measurement environments system. The performance of the absorber was also analyzed based on the equivalent medium model theory. Furthermore, the lumped element circuit model of the absorber was explained to verify the simulated resonance of reflection coefficients. The proposed absorber manifested excellent polarization insensitiveness until 45-degree. Meanwhile, the distribution of electromagnetic fields was analyzed to reveal the existence of electro-dipole resonance and magnetic resonance. In conclusion, the performances and diverse characteristics of the binary-coded metasurface absorber were identified to be compatible with integrated micro-circuit devices and encoding information at microwave frequency.

Miniature Electrodynamic Wireless Power Transmission Receiver Using a Micromachined Silicon Suspension

We present the design, modeling, fabrication, and experimental characterization of an electrodynamic wireless power transmission (EWPT) receiver for low-frequency (<; 1 kHz), near-field wireless power transmission. The device utilizes a bulk-micromachined silicon serpentine suspension, two NdFeB magnets and two precision-manufactured coils. The architecture of the transducer is designed to maximize the electrodynamic coupling coefficient while maintaining a low mechanical resonant frequency in order to maximize the power density for low-frequency wireless power transmission. An equivalent lumped-element circuit model is established to parameterize the system and to predict the output performance of the proposed system. A prototype device is fabricated, assembled and tested, and the results are compared with the model prediction. The 0.31 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> device generates 2.46 mW average power (7.9 mW·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> power density) at 4 cm distance from a transmitter coil operating at 821 Hz and safely within allowable human exposure limits. This data corresponds to a normalized power density of 21.9 mW·cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> ·mT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> , which is 44% higher than similar reported devices. Based on these results, this device shows great suitability for wirelessly charging mobile, wearable and bio-implantable devices. [2020-0161]