Ljiljana Živanov

Novel efficient methods for inductance calculation of meander inductor

Purpose – Present 3D electromagnetic simulators have high accuracy but they are time and memory expensive. Owing to a fast and simple expression for inductance is also necessary for initial inductor design. In this paper, new efficient methods for total inductance calculation of meander inductor, are given. By using an algorithm, it is possible to predict correctly all inductance variations introduced by varying geometry parameters such as number of turns, width of conductor or spacing between conductors.Design/methodology/approach – The starting point for the derivation of the recurrent formula is Greenhouse theory. Greenhouse decomposed inductor into its constituent segments. Meander inductor is divided into straight conductive segments. Then the total inductance of the meander inductor is a sum of self‐inductances of all segments and the negative and positive mutual inductances between all combinations of straight segments. The monomial equation for the total inductance of meander inductor has been obt...

Electrical and temperature characterization of NiZn ferrites

In this paper we investigate microstructure and electrical properties of NiZn ferrite ring cores and influence of different temperatures on these properties in the wide frequency range from 10 kHz to 1 GHz. Important electrical parameters are analyzed through measuring inductance, impedance and phase angle using LCZ meter HP4277A for lower frequency range (10 kHz-1 MHz) and RF Impedance analyzer HP4191A for higher frequencies (1 MHz-1 GHz). The complex permeability spectra of two ferrite materials, labeled with F14 and F19, has been calculated by means of these measured parameters. It can be concluded that, up to a certain frequency, permeability increases with temperature increase and above that frequency this behavior is opposite. The normalized temperature characteristics of permeability and impedance are also given for analyzed samples.

Parameters affecting the sensitivity of LTCC pressure sensors

Purpose – The purpose of this paper is to demonstrate the influence of material properties and fabrication technique on the performance of an embedded pressure sensor. Based on conducted theoretical analysis a suitable material and technological technique that gave the best behavior of designed sensor was chosen for its fabrication. This is verified on the example of a resonant pressure sensor, designed for operation in the MHz range.Design/methodology/approach – A sensor module is fabricated using the low temperature co‐fired ceramics (LTCC) technology and sputtering technique for electrodes deposition. The module comprises an inductor connected with a variable capacitor formed by the sensor membranes in a parallel LC circuit. An extensive parallel analysis of sensors performance for sensors with thick film (screen‐printed) and thin film (sputtered) electrodes is demonstrated. Mechanical and electrical parameters (Youngs modulus and permittivity) of different tape materials that are considered for senso...

RF equivalent circuit modeling of surface mounted components for PCB applications

Purpose – The appropriate selection of a testing method largely determines the accuracy of a measurement. Parasitic effects associated with test fixture demand a significant consideration in a measurement. The purpose of this paper is to introduce a measurement procedure which can be used for the characterization of surface mount devices (SMD) components, especially devoted to SMD inductors.Design/methodology/approach – The paper describes measurement technique, characterization, and extracting parameters of SMD components for printed circuit board (PCB) applications. The commercially available components (multi‐layer chip SMD inductors in the ceramic body) are measured and characterized using a vector network analyzer E5071B and adaptation test fixture on PCB board. Measurement results strongly depend on the choice of the PCB; the behaviour of the component depends on the environment where the component is placed.Findings – The equivalent circuit parameters are extracted in closed form, from an accurate ...

Characterization and modelling of miniature ferrite transformer for high frequency applications

Purpose – Significant achievements in ferrite material processing enable developments of many ferrite devices with a wide range of power levels and working frequencies, which make demands for new characterization and modelling methods for ferrite materials and components. The purpose of this paper is to introduce a modelling and measurement procedure, which can be used for the characterization of two‐port ferrite components in high frequency range.Design/methodology/approach – This paper presents a commercially available ferrite component (transformer) modelling and determination of its electrical parameters using in‐house developed software. The components are measured and characterized using a vector network analyzer E5071B and adaptation test fixture on PCB board. The parameters of electrical equivalent circuit of the ferrite transformer parameters are compared with values extracted out of measured scattering parameters.Findings – A good agreement between modelled and extracted electrical parameters of...

Embedded Ferrite LTCC Inductors

This paper presents for the first time one realization of simple planar inductor realized inside the stack of ferrite LTCC (Low Temperature Co-fired Ceramic) tapes. Presented inductor is one layer square spiral fabricated in the LTCC technology. In order to point out benefits of implementation of ferrite material on inductor inductance, the same inductor geometry was fabricated between two dielectric LTCC tapes. Commercially available LTCC material (both ferrite and dielectric) were implemented for the realization of proposed inductors. Designed structures were characterized and obtained experimental results show that even implementation of a very thin layer of ferrite material around inductor lines drastically increases its inductance. For the same inductor design that occupies the same chip area the inductance enhancement over 11 times is achieved. In addition this enhancement is followed with maintenance of good performance of the inductor.

Influence of substrate thickness on performance of LTCC micro-transformer

This paper presents one aspect of research regarding various possibilities for performance improvement of integrated passive components. The paper deals with influence of substrate thickness on properties of spiral micro-transformer fabricated in LTCC technology. Designed geometry represents an interleaved spiral transformer printed on the top of one LTCC dielectric tape embedded in seven separate substrates that incorporate one to seven bottom tape layers. Obtained results of experimental characterization show trend of transformer performance improvement with increase of substrate bottom layers of transformer module. Inductance, Q-factor and coupling coefficient of transformer windings exhibit more than double enhancement of their values, while mutual inductance increases almost four times, in the lower RF frequency range. However, after certain limit increase of substrate thickness does not contributte much to transformers performance. This implies that optimal substrate thickness can be determined in order to obtain the best properties of micro-transformers.

Capacitance Dependence of Interdigital Capacitor on Amount and Type of Applied Liquid

In this paper design and fabrication of three types of interdigital capacitors are discussed, as well as influence of the liquid amount on their capacitance, and possibility of liquid type determination by using the fabricated structures. For faster and more reliable determination of capacitance in dependence of capacitor dimension and used substrate, a software tool called INDICON was developed. Capacitance of three structures fabricated in conventional PCB technology was determined by measuring S-parameters. Measurements were also performed by adding the exact amount of liquids on the capacitor surface. In addition, capacitance value in dependence of liquid amount is presented and possibility of applying this structure for detection of liquid amount is analyzed. Also, capacitance value in dependence of used liquid types was shown. For all measured and calculated values good agreement is achieved.

Performance Improvement of RF Inductors Using LTCC Technology

This paper presents for the first time a parallel comparison of the performance of RF inductors realized on different substrate configurations. Presented inductors are meander type structures fabricated in Low Temperature Co-fired Ceramic (LTCC) technology. Also, chosen material is never before implemented for inductor fabrication. The performance improvement is achieved by design optimization of different substrate configurations that incorporate placement of an air-gap beneath the inductor and/or introduction of an additional shielding layer on the top. Designed structures are characterized on the basis of simulation and experimental data, achieving good correlation between obtained results. Presented results show over 30 % increase in quality factor and widening of the operating frequency range by over 55 %.

Wide Frequency Characterization of Magnetic Properties of Commercial LTCC Ferrite Material

Complex magnetic permeability and hysteresis characteristic are key parameters that determine properties of ferrite components. This paper offers effective, accurate and simple method for complex permeability determination of LTCC (Low Temperature Co-fired Ceramic) ferrite sample at wide frequency range (up to 1 GHz). Presented research can be found to be of importance in fields of ferrite components design and application, as well as RF and microwave engineering. The characterization sample is a stack of LTCC tapes forming a toroidal shape structure. Commercially available ferrite tape ESL 40012 was used and standard LTCC processing applied for the sample fabrication. Permeability is determined in the frequency range from 10 kHz to 1 GHz and characterization procedure is divided in two segments - for low and high frequencies. Low frequency measurements (from 10 kHz to 1000 kHz) are performed using LCZ meter and discrete turns of wire, while a short coaxial sample holder and Vector Network Analyzer were u...