Wideband Equivalent Circuit Research Articles

Analysis of IGBT Pseudodesaturation Effect Caused by Stray Parameters in DC Circuit Breaker

As a highly integrated high-voltage power electronic equipment in the power grid, the DC circuit breaker (DCCB) has misjudged overcurrent protection caused by the IGBT pseudo desaturation effect (PDE) in DC short-circuit fault. To analyze the reasons for the effect, this paper established a wide-band equivalent circuit model of a hybrid high-voltage DCCB at the initial stage of DC fault. And revealed the mechanism of PDE: the stray inductance of series-connected solid-state switches, the junction capacitance of metal oxide varistors (MOVs), and the parasitic capacitance to the ground of DCCB form multiple resonant circuits. The external disturbance is converted into the interference of DCCB port through these stray parameters, and the interference would exceed the IGBT desaturation detection threshold. Furthermore, an equivalent experimental circuit that reproduces the electromagnetic interference of DCCB at the DC fault transient process was proposed, and the correctness of the mechanism analysis was verified by the scaled prototype of DCCB, the main resonance frequency error is less than 15%. Finally, the frequency domain and time domain characteristics of electromagnetic interference on the IGBT desaturation detection monitoring ports in 200kV DCCB at the initial stage of DC fault were analyzed. Based on these characteristics, a scheme of adding a delay time to the overcurrent protection criterion to avoid electromagnetic interference was proposed, which is adopted by an industrial project.

A Wideband Equivalent Circuit Electric Dipoles

The problem of obtaining a wideband equivalent circuit for dipole antennas is addressed backward; the four-element circuit topology is taken as given; its three-element part was suggested by Chu and its extension to four elements by Stuart. The goals here are to obtain the element values with the least effort and to explore the available bandwidth. Based on the impedance spectrum, rather than on radiation or current eigenmodes, this approach identifies elements of the circuit from their behavior with frequency over a wideband impedance spectrum that includes both first and second resonances. Element values are derived from their impedance behaviors at three frequencies: zero (dc), first (series or short-circuit), and second (parallel or open-circuit) resonance. An Argand diagram is introduced to determine ${R}$ and ${L}$ at the first resonance; the two capacitances, ${C}$ and ${C} _{t}$ , at first and second resonances, respectively, complete the circuit. Optimization follows. Several examples are given and limitations discussed.

An improved wideband equivalent circuit model for integrated spiral inductors in CMOS technology

AbstractThis paper presents an improved wideband single‐π model for on‐chip spiral inductors based on the independent tested ground PADs (ITGPs). For the ITGP, the input and output ground PADs are not connected together that introduces potential difference between the input and output ground PADs. However, the conventional inductor models are suitable for the ground PADs being connected together; they usually ignore the input and output potential difference and failed to achieve high model accuracy for the ITGP structure. To develop an accurate model for ITGP, the potential difference between input and output ground PADs is analyzed in this paper, and then the lumped‐parameter resistor‐capacitor network is used to characterize it. To validate the proposed model, the test structures were fabricated by 0.18‐μm CMOS technology and measured up to 67 GHz. Compared with the conventional model, the calculation results of the proposed model agree the measurement results better. Furthermore, the root mean square errors (RMSEs) of proposed model are less than 0.025.

Ultra Wide Band CPW-Fed Circularly Polarized Microstrip Antenna for Wearable Applications

A conformal rigid microstrip ultra-wideband (UWB) circularly polarized wearable antenna is proposed to overcome the behavioural irregularities of flexible body-worn antennas. The design demonstrates the inclusion of two L shaped radiators along with an L shape feed and also a vertically protruded stub embedded with the ground plane for achieving the required ultra-wide bandwidth and circular polarization. Coplanar waveguide (CPW) feed is used to overcome the bandwidth limitation of circular polarization. The proposed low profile antenna with dimensions 75 × 63 × 1.52 mm3 yields a 10 dB impedance bandwidth of 111.4% (1.28–4.5 GHz) and a 3 dB axial ratio bandwidth of 45.61% (2.2–3.5 GHz). On body performance measurement of this planar antenna validates its applicability under body worn condition. Specific absorption rate (SAR) assessment has also been evaluated for this antenna on a hypothetical body model to justify its acceptance for the wearable application. It is observed that the maximum radiation amount absorbed by the body model is restricted to a maximum SAR value of 1.19 W/kg and 1.43 W/kg over 1 g and 10 g average body mass respectively. The time-domain characteristics such as group delay and waveform response, also exhibit satisfactory UWB performance of the proposed antenna. A lumped wideband equivalent circuit model of the antenna is also developed for estimating the broadband matching ability.

Research on Overvoltage Distribution of HVDC Converter Valve in Special Environment

HVDC transmission technology has great advantages in long-distance, large-capacity cross-region power transmission. Thyristor converter valve is the core equipment of HVDC transmission technology, and its reliability directly affects the reliability of the whole system. During the operation of HVDC transmission system, it will face the special operating environment, including high altitude nuclear electromagnetic pulse(HEMP), operating overvoltage, lightning, and steep wave overvoltage. In order to study the reliability of the converter valve under special circumstances, the wideband equivalent circuit model of the key components were built in this paper. On this basis, the overvoltage distribution inside the converter valve under special environments is simulated and analyzed. The results show that the overvoltage distribution inside the converter valve system is related to the characteristic parameters of the special environment, and the distribution trend of the overvoltage of the saturated reactor and the thyristors is also different, so the weak components of the converter valve system under special circumstances can be obtained. It has certain reference value for studying the reliability of the converter valve system under special circumstances.

Parameterised equivalent circuit model of frequency‐dependent resistance and inductance for on‐chip coplanar waveguides up to 110 GHz

A parameterised wideband equivalent circuit model capturing the per-unit-length (p.u.l.) frequency-dependent resistance and inductance of on-chip coplanar waveguides (CPWs) is presented. The parameterised model for on-chip CPWs is suitable for various process nodes and over a large geometry range with signal line width-to-thickness ratios w s / t between 1 and 15 and spacing-to-thickness ratios s / t between 0.25 and 15. The model has been validated by both EM simulation and measurements of fabricated test chips. The model is accurate to within 10% over the normalised geometry range. The model can easily be implemented into standard circuit simulators.

Scalable wideband equivalent circuit model for silicon-based on-chip transmission lines**Project supported by National Natural Science Foundation of China (No. 61674036).

A scalable wideband equivalent circuit model of silicon-based on-chip transmission lines is presented in this paper along with an efficient analytical parameter extraction method based on improved characteristic function approach, including a relevant equation to reduce the deviation caused by approximation. The model consists of both series and shunt lumped elements and accounts for high-order parasitic effects. The equivalent circuit model is derived and verified to recover the frequency-dependent parameters at a range from direct current to 50 GHz accurately. The scalability of the model is proved by comparing simulated and measured scattering parameters with the method of cascade, attaining excellent results based on samples made from CMOS 0.13 and 0.18 μm process.

An Improved 100 GHz Equivalent Circuit Model of a Through Silicon Via With Substrate Current Loop

This letter presents a new wideband equivalent circuit model for through silicon via (TSV) with consideration of the effective substrate current loop in silicon substrate and proximity effect on the currents in the TSV. The proposed model can accurately predict the electrical performance of the TSV at wide frequency range. The proposed model correlates well up to 100 GHz when compared to the full-wave electromagnetic simulation.

Wideband Equivalent Circuit for Multi-Aperture Multi-Resonant Waveguide Irises

In this paper it is shown that the traditional shunt admittance represented by a rational function yields an accurate wideband equivalent circuit for multi-aperture waveguide irises. The electromagnetic analysis of the structures reveals two different types of resonant phenomena. The first type of resonance is associated with the cutoff frequency of the ${\rm TE}_{10}$ mode. The second type or antiresonace corresponds to short-circuit TEM modes. These antiresonances are generated when the asymmetry of the iris allows the excitation of electric fields with opposite phases at contiguous apertures. The proposed equivalent circuit is a shunt admittance represented by a rational function. This rational function is analytically obtained from the singular points (resonances and antiresonances) identified in the full-wave analysis. It is straightforward to obtain the circuit elements from the rational function by following the classical one-port synthesis leading to Foster’s or Cauers’s canonical realizations. One advantage of the proposed equivalent circuit is that it represents the electromagnetic behavior of complicated structures with a minimum number of circuit elements or degrees of freedom. Several examples, with different number of apertures and symmetry, are presented to illustrate the proposed general equivalent circuit. Finally, the proposed procedure is extended to the case of arbitrary shaped irises, such as those used in frequency-selective surfaces.

Low-Loss Air-Cavity Through-Silicon Vias (TSVs) for High Speed Three-Dimensional Integrated Circuits (3-D ICs)

Since the coupling loss of conventional low resistivity silicon (LRSi) is considerable in high speed three-dimensional integrated circuits (3-D 'Cs), air-cavity through-silicon vias (TSVs) on LRSi are proposed in this letter to reduce the conductive substrate losses for microwave applications. The Q-factor and insertion loss are exploited to assess the effect of air-cavity TSVs. The accurate wideband equivalent circuit model and simplified π-model are derived based on the physical design parameters, which are established by the ADS software. Well agreements between the proposed models and 3-D full-wave EM field simulation of Ansoft's HFSS are shown with the operating frequencies up to 20 GHz.

Wideband analytical equivalent circuit for one-dimensional periodic stacked arrays.

A wideband equivalent circuit is proposed for the accurate analysis of scattering from a set of stacked slit gratings illuminated by a plane wave with transverse magnetic or electric polarization that impinges normally or obliquely along one of the principal planes of the structure. The slit gratings are printed on dielectric slabs of arbitrary thickness, including the case of closely spaced gratings that interact by higher-order modes. A Π-circuit topology is obtained for a pair of coupled arrays, with fully analytical expressions for all the circuit elements. This equivalent Π circuit is employed as the basis to derive the equivalent circuit of finite stacks with any given number of gratings. Analytical expressions for the Brillouin diagram and the Bloch impedance are also obtained for infinite periodic stacks.

Accurate Circuit Modeling of Fishnet Structures for Negative-Index-Medium Applications

Metallic plates with a two-dimensional (2D) periodic distribution of sub-wavelength apertures are known to exhibit extraordinary transmission of electromagnetic waves. Stacking two or more of such plates gives place to the so-called fishnet structures, which constitute a popular way of achieving an effective negative index medium at frequencies ranging from microwaves to optics. Unfortunately, a general wideband equivalent circuit has not yet been proposed to facilitate its understanding and design. This work presents this circuit model with closed-form expressions for the circuit elements, thus making it possible to obtain the electrical response for this class of structures in a very efficient way. This procedure is much faster than alternative numerical methods at the same time that it retains a high level of accuracy when compared with some other oversimplified models. The circuit model also provides a simple rationale as well as a good physical insight in order to explain the qualitative behavior of such structures, independently of the number of stacked layers.

Wideband Impedance Model for Coaxial Through-Silicon Vias in 3-D Integration

Coaxial through-silicon via (TSV) is a promising 3-D integration solution, which can offer lower coupling with its surrounding environment and achieve better electromagnetic compatibility and signal integrity than other TSV structures. In this paper, an analytical wideband equivalent circuit model is proposed for the impedance modeling of coaxial TSVs in 3-D integration. Closed-form formulas for calculations of the per-unit-length resistance and the inductance of both the isolation dielectric filled and silicon filled coaxial TSVs are derived from the theory of quasi-magnetostatic fields. These formulas appropriately capture the skin effect in metal as well as the eddy current effect in silicon. Therefore, they yield accurate results comparable with the full-wave solutions in a wideband frequency range.

A Modeling Method of Wideband Devices Based on Modified Nodal Analysis

According to the simplified circuit partitioning principle, this paper improves the Modified Nodal Analysis(MNA) of wideband Equivalent Circuit Model(ECM). The form of upconversion impedance is transformed from series into parallel. The results show that in the parallel form, the verification process of impedance type has been eliminated and it will not introduce new nodes. At the same time, the amount of computation has been reduced. The maximum relative error of measured data with this model fit is less than 0.693%. The simulation results and ECM test data are consistent with better at 0 to 8GHz frequency range.

Millimeter-wave balanced mixer based on a novel wide-band Schottky diode model

A Schottky diode model for the mixer's design is presented in this paper.According to the physical structure of the Schottky diode,a novel 3D electromagnetic(EM) model was built and analyzed by finite element method.A wide-band equivalent circuit up to 110 GHz was proposed taking the parasitic effects distributed in the diode into account.Based on the proposed equivalent circuit,a Ka-band balanced mixer was designed and optimized.The measured conversion loss is 7.5 dB to 10 dB from 32 GHz to 37 GHz,which agreed well with the simulated one.

Compact Wideband Equivalent-Circuit Model for Electrical Modeling of Through-Silicon Via

This paper presents a compact wideband equivalent circuit model for electrical modeling of through-silicon vias (TSVs) in 3-D stacked integrated circuits and packaging. Rigorous closed form formulas for the resistance and inductance of TSVs are de rived from the magneto-quasi-static theory with a Fourier-Bessel expansion approach, whereas analytical formulas from static solutions are used to compute the capacitance and conductance. The equivalent-circuit model can capture the important parasitic effects of TSVs, including the skin effect, proximity effect, lossy effect of silicon, and semiconductor effect. Therefore, it yields accurate results comparable to those with 3-D full-wave solvers.

Design of a Compact Ka-band Balanced Mixer Based on a Novel Wide-band Equivalent Circuit of the Schottky Diode

A compact Ka-band balanced mixer based on a novel Schottky diode model is presented in this paper. According to its physical structure, a novel 3D electromagnetic model of the Schottky diode is proposed. Meanwhile, a wide-band equivalent circuit is built, which takes all high frequency effects existing in the diode into account. All the parasitic reactances are extracted from the electromagnetic model-based S-parameters up to 110 GHz. Based on the proposed equivalent circuit, a Ka-band balanced mixer is designed and optimized, where bandpass filters with open stubs and a lowpass filter based on defected ground structure cells are used. The measured results show that the conversion loss is below 9 dB from 30 GHz to 40 GHz with the minimum of 6.7 dB at 35 GHz. The normalized size of the mixer is only 3.3λ g × 3.3λ g , whereλ g is the wavelength at 35 GHz.

Wideband characterization of SOI materials and devices

In the present paper, the interest of wideband characterization for the development of integrated technologies is highlighted. The extraction of electrical equivalent circuits for passive and active devices in silicon-on-insulator (SOI) technology is described. The electrical characteristics of the SOI substrate versus DC bias and high frequency signal is presented as well as the wideband behavior of several advanced MOSFETs, such as 120 nm partially depleted (PD) SOI MOSFETs, 120 nm dynamic threshold (DT) voltage MOS, 50 nm FinFETs as well as long-channel planar double gate MOSFETs. Based on these wideband equivalent circuits, RF designers can define optimized circuits and precious information can be delivered to engineers for the improvement of the fabrication process as well.

Frequency-independent equivalent circuit model for ferromagnetic RF integrated inductors

We have proposed a method for identifying a wide-band equivalent circuit model for ferromagnetic radio frequency (RF) integrated inductors. The equivalent circuit parameters have been extracted from measured S-parameters by using a multiobjective simplex method, which sequentially switches three different cost functions, given by the average of error in Y-parameters, Z-parameters, and S-parameters. With this method, the optimization converged to the global minimum without being trapped at a local minimum. Calculated Y-parameters, Z-parameters, and S-parameters were in good agreement with the measured results in the range of dc to 20 GHz.

Electrical characterization and structure investigation of quad flat non-lead package for RFIC applications

The quad flat non-lead (QFN) package is a both chip scale package and plastic encapsulated package with a copper leadframe substrate. The purpose of this paper was to establish the wideband equivalent circuit model of QFN packages for RF applications. Only short-path configuration was required for S-parameter measurement to achieve this purpose. Comparison of S 11 and S 21 between S-parameter measurement and optimized equivalent circuit model verified that those results were well matched and optimized. The parasitic parameters of the equivalent circuit were reliable up to 6 GHz. The methods proposed in this paper reduce the costs for samples preparation and chip simulation run time. In order to realize the package performance for higher frequency applications further, a 3D structure electromagnetic field simulator, HFSS, was used to simulate from 0.1 to 20 GHz for five modified package structures. Simulation results indicated that the QFN32 package that utilized the double bonding wires with a lower dielectric-constant molding compound and larger die-pad is the best structure for RF applications.