CiteULike: dcastro's interdigital

Adjustable Bandwidth Filter Design Based on Interdigital Capacitors

Li Zhu — 2008-04-16T19:38:04-00:00

Microwave and Wireless Components Letters, IEEE, Vol. 18, No. 1. (2008), pp. 16-18.

In this letter, we explore a general-purpose microstrip coupling model for computer aided design of new bandpass filters. The J-inverter topology of the model facilitates the study of coupling behaviours of different microstrip structures leading to a quick comparison of their coupling strengths. Based on such comparison, microstrip filters with interdigital capacitors and etched slots yielding relatively higher coupling coefficients are designed, fabricated and tested. The filters exhibit relatively wider bandwidths which are easily adjustable by way of changing the geometrical parameters of interdigital capacitors and slots.

Modeling and design of interdigital structure

RT Kollipara — 2008-04-16T19:37:43-00:00

Electron Devices, IEEE Transactions on, Vol. 38, No. 11. (1991), pp. 2575-2577.

A computer-aided-design-compatible model is described for an interdigital structure in microstrip configuration. The interdigital structure is modeled by using the admittance matrix of the coupled microstrip lines and modified to include the discontinuities and the distributed elements. The model takes into account all the distributed effects of the structure and models them as circuit elements. The equivalent circuit elements of the interdigital structure are computed in closed-form expressions. The results are compared with other models and also with the experimental results. Even though the model does not consider the phase shift along the terminal strip, it is shown to be valid well into the gigahertz range

Equivalent capacitances of coplanar waveguide discontinuities and interdigitated capacitors using a three-dimensional finite difference method

M Naghed — 2008-04-10T06:44:30-00:00

Microwave Theory and Techniques, IEEE Transactions on, Vol. 38, No. 12. (1990), pp. 1808-1815.

Equivalent capacitances of coplanar waveguide discontinuities on multilayered substrates are calculated using a three-dimensional finite-different method. The application of the method is demonstrated for open ends and gaps in microstrip and coplanar waveguides, as well as for more complicated structures such as interdigitated capacitors. The main advantage of the method is its flexibility in treating multilayered substrates and different conductor configurations. It can therefore be applied to more complicated structures such as interdigitated capacitors, air bridges, and waveguide transitions. The effect of conductor metallization thickness and shielding walls is also taken into account. Good agreement between the calculated data and measurements up to 25 GHz in the case of coplanar structures indicates the validity of the static analysis even for high frequencies

Compact high-impedance surfaces incorporated with interdigital structure

Y Fu — 2007-11-27T10:26:41-00:00

Electronics Letters, Vol. 40, No. 5. (2004), pp. 310-311.

A novel compact high-impedance surface structure is presented. The periodic branched elements cross over like interdigital capacitors. This structure is adopted to increase the fringe capacitor in order to compress the overall size of the high-impedance surface. Measured results show that 30-40% size reduction could be obtained.

A general-purpose circuit model of interdigital capacitor for accurate design of low-loss microstrip circuit

Lei Zhu — 2007-11-27T10:24:18-00:00

Microwave Symposium Digest, 1998 IEEE MTT-S International, Vol. 3 (1998), pp. 1755-1758 vol.3.

A general-purpose CAD-oriented circuit model is presented for accurately modeling interdigital capacitor (IDC) in optimized design of low-loss IDC-related microstrip circuits. This equivalent model is formulated as an admittance-based π-network through the use of a so-called “Short-Open Calibration (SOC)” technique for extracting precisely circuit parameters from a fullwave method of moments (MoM). A J-inverter based topology is further developed for explicit characterization of IDC-related coupling characteristics that accounts for frequency dispersion and fringing effect. Extracted model parameters are given for two types of IDC structure and the model accuracy is well validated by our experiments for an IDC-related quasi-lumped bandpass filter

Corrections to "accurate circuit model of interdigital capacitor and its application to design of new quasi-lumped miniaturized filters with suppression of harmonic resonance"

Lei Zhu — 2007-11-27T10:23:01-00:00

Microwave Theory and Techniques, IEEE Transactions on, Vol. 50, No. 10. (2002), pp. 2412-2413.

DGS resonator with interdigital capacitor and application to bandpass filter design

JS Park — 2007-11-27T10:19:53-00:00

Electronics Letters, Vol. 40, No. 7. (2004), pp. 433-434.

A novel defected ground structure (DGS) microstrip resonator is proposed. The proposed DGS resonator has the resonant and anti-resonant characteristic that is very similar to those of a surface acoustic wave resonator or a film bulk acoustic resonator (FBAR). To confirm the validity of the proposed resonator, bandpass filters were designed and implemented using series and parallel resonators.

A miniaturized interdigital microstrip bandpass filter

Kao-Cheng Huang — 2007-11-26T20:31:03-00:00

Applied Superconductivity, IEEE Transactions on, Vol. 9, No. 2. (1999), pp. 3889-3892.

A 2.4 GHz three-stage microstrip bandpass filter was designed using a miniaturized interdigital capacitor structure to reduce the configuration in size. The filter was simulated by a finite element method software and then fabricated using TBCCO superconducting films on 20 mm×20 mm×0.5 mm MgO substrates. It was generated by photolithographic and wet etching process and packaged in a brass box. The bandwidth is 4% and the passband insertion loss of the filter was measured to be -0.4 dB at 77 K. The return loss is better than -8 dB. In particular, this filter has a sharper performance at its edge of fundamental pass band

Interdigital Capacitors for Use in Lumped-Element Microwave Integrated Circuits

GD Alley — 2007-11-26T20:29:15-00:00

Microwave Symposium Digest, G-MTT International, Vol. 70, No. 1. (1970), pp. 7-13.

An analysis of the frequency response of interdigital capacitors is given along with an equation for their design. The capacitor Q is given in terms of its geometry which consists of a planar interdigital conductor deposited on the surface of a substrate. Capacitance values ranging from 0.1 to 10 pF at L band with measured Q's in excess of 400 are realizable.

Wire bonded interdigital capacitor

FP Casares-Miranda — 2007-11-26T20:27:05-00:00

Microwave and Wireless Components Letters, IEEE, Vol. 15, No. 10. (2005), pp. 700-702.

Interdigital capacitors (IDCs) are convenient capacitance devices in microstrip circuits, even if only low capacitance values can be achieved. Nevertheless, undesired resonances degrade their performance when frequency increases. Short circuits across the end of alternate fingers of the IDC improve its high frequency response by eliminating that drawback. Simulated and measured results are presented.

CAD models for multilayered substrate interdigital capacitors

SS Gevorgian — 2007-11-26T20:11:54-00:00

Microwave Theory and Techniques, IEEE Transactions on, Vol. 44, No. 6. (1996), pp. 896-904.

Conformal mapping-based models are given for interdigital capacitors on substrates with a thin superstrate and/or covering dielectric film. The models are useful for a wide range of dielectric constants and layer thicknesses. Capacitors with finger numbers n&ges;2 are discussed. The finger widths and spacing between them may be different. The results are compared with the available data and some examples are given to demonstrate the potential of the models

Accurate circuit model of interdigital capacitor and its application to design of new quasi-lumped miniaturized filters with suppression of harmonic resonance

Lei Zhu — 2007-11-26T20:06:00-00:00

Microwave Theory and Techniques, IEEE Transactions on, Vol. 48, No. 3. (2000), pp. 347-356.

A general-purpose circuit model of a microstrip interdigital capacitor (IDC) is presented in this paper for use in the design of new quasi-lumped miniaturized filters. This computer-aided-design-oriented model is developed as a versatile admittance π-network with the short-open calibration technique that we have recently proposed for accurate parameter extraction of a circuit from its physical layout. This technique is self-contained in our method of moments, which accounts for frequency dispersion and fringing effects. A J-inverter topology is further conceived to explicitly formulate the coupling behavior of three types of IDC's. This model provides a unique way for the IDC-related circuit synthesis and optimization based on the accurate equivalent-circuit network extracted from the field theory algorithm. It is validated theoretically and experimentally through an example of a line resonator connected with two IDC's. The proposed scheme is used in the design and optimization of new low-loss miniaturized quasilumped integrated circuits, namely, two types of three-pole direct-coupled bandpass filters. Our measured and predicted results show interesting features of the proposed filter structure such as size reduction and suppression of harmonic resonance if the line resonator is attached by series-connected equivalent inductance

Analysis of interdigital capacitor and quasi-lumped miniaturized filters using iterative method

A Gharsallah — 2007-11-26T20:05:31-00:00

International Journal of Numerical Modelling: Electronic Networks, Devices and Fields, Vol. 15, No. 2. (2002), pp. 169-179.

This paper presents the application of an iterative method for fast computation of microstrip interdigital capacitor (IDC) and a quasi-lumped miniaturized filter. The use of a 2D-FFT algorithm allows simplifications in the calculation process leading to accurate results obtained 20 times faster than in the conventional method cases. Copyright © 2002 John Wiley & Sons, Ltd.

Interdigital Capacitors and Their Application to Lumped-Element Microwave Integrated Circuits

GD Alley — 2007-11-26T20:04:40-00:00

Microwave Theory and Techniques, IEEE Transactions on, Vol. 18, No. 12. (1970), pp. 1028-1033.

An analysis of the frequency response of interdigital capacitors, which leads to an optimal design, is given along with an expression for their static gap capacitance. The capacitor Q is given in terms of its geometry which consists of a planar interdigital thin-filrn conductor deposited on the surface of a relatively high dielectric constant substrate. Capacitance values ranging from 0.1 to 10 pF at L band with measured Q's in excess of 400 are realizable using 2-mil line and space widths on a 99.5-percent alumina substrate with a dielectric constant of 10.3. Experimental results obtained with a lumped-constant nine-section S-band Chebyscheff low-pass filter realized using spiral inductors and optimal designed interdigital capacitors are shown to be in excellent agreement with theory. The filter had less than 0.8-dB insertion loss and greater than 25dB return loss in the passband. The filter occupies an area 6.50 by 200 roils on a 24-mil-thick substrate.

Superconducting microstrip filters using compact resonators with double-spiral inductors and interdigital capacitors

Jiafeng Zhou — 2007-11-14T17:46:09-00:00

Microwave Symposium Digest, 2003 IEEE MTT-S International, Vol. 3 (2003), pp. 1889-1892 vol.3.

Novel resonators composed of double-spiral inductors and interdigital capacitors are developed, which not only are compact in size but also have no harmonics up to three times of the fundamental frequency. The center frequency is insensitive to the thickness of the substrate. A miniature seven-pole narrow-band HTS bandpass microstrip filter has been designed, fabricated and tested for an astronomy observation application, which requires a center frequency at 610 MHz and 0.82% fractional bandwidth. The computed and measured results are found in excellent agreement.

Composite Right/Left-Handed Transmission Line With Wire Bonded Interdigital Capacitor

FP Casares-Miranda — 2007-11-07T18:39:01-00:00

Microwave and Wireless Components Letters, IEEE, Vol. 16, No. 11. (2006), pp. 624-626.

An enhanced composite right/left-handed (CRLH) transmission line (TL) is presented in this letter. This TL, designed in microstrip technology, is implemented by means of a new improved interdigital capacitor (IDC), the so-called wire bonded IDC (WBIDC). The use of the WBIDC broadens the frequency band where the CRLH TL can be considered as a TL. A conventional 70-Omega CRLH TL (using IDCs) has been compared, by full-wave simulation and measurements, with its enhanced counterpart (using WBIDCs). In addition, this enhanced CRLH TL has been used to design a CRLH diplexer which presents several advantages over standard CRLH coupled lines (using IDCs). The diplexer response has been verified by means of a full-wave electromagnetic solver

Analytical model of the wire-bonded interdigital capacitor

E Marquez-Segura — 2007-11-07T18:38:40-00:00

Microwave Theory and Techniques, IEEE Transactions on, Vol. 54, No. 2. (2006), pp. 748-754.

The wire-bonded interdigital capacitor (WBIDC) is an interdigital capacitor with short circuits across the end of alternate fingers that result in an improved frequency response. This paper presents the analytical and circuital models of the WBIDC, which are useful to design and to incorporate into an electromagnetic or circuit analysis computer-aided design program. Design equations of the WBIDC are also presented. The analytical model and design equations have been validated with numerical analysis and experimental work.