Ariana L. C. Serrano

Synthesis Methodology Applied to a Tunable Patch Filter With Independent Frequency and Bandwidth Control

A new methodology for the synthesis of tunable patch filters is presented. The methodology helps the designer to perform a theoretical analysis of the filter through a coupling matrix that includes the effect of the tuning elements used to tune the filter. This general methodology accounts for any tuning parameter desired and was applied to the design of a tunable dual-mode patch filter with independent control of center frequency and bandwidth (BW). The bandpass filter uses a single triangular resonator with two etched slots that split the fundamental degenerate modes and form the filter passband. Varactor diodes assembled across the slots are used to vary the frequency of each degenerate fundamental mode independently, which is feasible due to the nature of the coupling scheme of the filter. The varactor diode model used in simulations, their assembling, the dc bias configuration, and measured results are presented. The theory results are compared to the simulations and to measurements showing a very good agreement and validating the proposed methodology. The fabricated filter presents an elliptic response with 20% of center frequency tuning range around 3.2 GHz and a fractional BW variation from 4% to 12% with low insertion loss and high power handling with a 1-dB compression point higher than .

A tunable bandpass patch filter with varactors

This paper presents a miniaturized tunable bandpass patch filter using varactors. The filter is conceived with a triple-mode circular patch resonator with four slots, where the varactors were connected. The extracted equivalent model, the varactors assembly configuration and their biasing are presented. A DC bias from 0 to 20 V was applied to vary the filters center frequency from 2.35 GHz to 1.8 GHz and its 3-dB fractional bandwidth from 31.5% to 8.5%. Within these variations, all measurements showed insertion loss lower than 2 dB and return loss better than 10 dB over the passband, ensuring a good quality factor.

Analysis of a Reconfigurable Bandpass Circular Patch Filter

This paper presents an analysis of a reconfigurable patch filter based on a triple-mode circular patch resonator with four radial slots. The analysis has been carried out thanks to the development of a new theoretical approach of the tunable patch filter based on the coupling matrix. The coefficients of the coupling matrix related to the tunable behavior have been identified and some rules for their evolution have been derived. For a proof-of-concept, a bandpass filter has been designed with a continuous tunability obtained with varactors connected across the slots. State-of-the-art results have been obtained, with a frequency tuning range of 27% from 1.95 to 2.43 GHz and a change in fractional bandwidth from 8.5% to 31.5% for the respective frequencies. In the entire tuning range, the return loss is better than 10 dB and the maximum insertion loss is 2 dB. Due to the newly developed coupling matrix, measurements, simulations, and theory showed great agreement.

Modeling and Characterization of Slow-Wave Microstrip Lines on Metallic-Nanowire- Filled-Membrane Substrate

In this paper, a physical model of the slow-wave (SW) microstrip lines based on a metallic-nanowire-filled-membrane substrate is presented for the first time. The model properly predicts the behavior of the SW transmission lines as shown by the experimental results. Two sets of transmission lines differing in oxide thickness with various widths were fabricated and characterized up to 70 GHz. The electrical model is valid for both oxide thicknesses and microstrips width. High-quality factors are obtained, above 40 from 30 GHz up to 70 GHz, paving the way for further designs of passive circuits, like power dividers or hybrid couplers, with good performance.

Slow-wave microstrip line on nanowire-based alumina membrane

This paper proposes a new technology for slow wave microstrip lines based on a low-cost metallic-nanowire-filled-membrane substrate (MnM-substrate). These transmission lines can operate from RF to millimeter-wave frequencies. The MnM-substrate consists in a dielectric material containing vertical metallic nanowires connected to a bottom ground plane. The innovative concept of the slow-wave microstrip lines on MnM-substrate is presented, as well as the electromagnetic considerations, fabrication process, and measurement results. Initial results show high relative dielectric constants (up to 43). Hence, it is possible to reach high-quality factor transmission lines within a great range of impedances, from 20 to 100 Ω, without critical dimensions.

A miniaturized bandpass filter with two transmission zeros using a novel square patch resonator

This paper presents a miniaturized square patch resonator with two different pairs of etched slots for bandpass filter applications. The slots split the fundamental degenerate modes of the resonator and allow the control of both central frequency and bandwidth, providing filter design flexibility. A two- and a four-pole filter centered at 2.4 GHz were designed using the same resonator and fabricated. Experimental results of the two-pole filter showed a bandwidth of 14%, return loss better than 18 dB, and minimum insertion loss of 0.6 dB. This filter exhibited a size reduction of 49% compared to an unperturbed square patch resonator at the same frequency. The four-pole filter results showed a bandwidth of 9.8%, and 33 dB rejection at the second harmonic band.

Development of MEMS varactor for selectable-band patch filter

The use of MEMS as tuning elements is interesting for their higher performance in terms of loss and nonlinearity. Here, MEMS varactors are integrated to a patch filter through a flip-chip process in order to change the filter center frequency. The selected frequencies are the ones assigned to WiMAX frequency bands at 2.5 GHz and 3.5 GHz.

Metallic nanowire filled membrane for slow wave microstrip transmission lines

A new concept of slow wave microstrip transmission lines (SW μTL) dedicated to mmW and sub-mmW applications (100 GHz and further) is described herein. The microstrip is deposited on a specific substrate consisting in a metallic nanowires-filled membrane (MnM) of alumina covered with a thin top layer of silicon oxide. The slow wave effect is obtained thanks to metallic nanowires that capture the electric field while the magnetic field can extend in the whole substrate. Despite of the strong miniaturization expected, such SW μTLs should reach a quality factor five times higher than the one obtained with a conventional microstrip line (without nanowires). Such SW μTL can act as interconnecting paths if the MnM substrate is used as a 3D-interposer.

3D inductors with nanowire through substrate vias

This paper presents a novel 3D inductor (solenoid) fabricated on a 50-pm thick AAO membrane using nanowire-vias. Several inductors were fabricated in this simple and low-cost technology with nanowires. They were measured up to 110 GHz and compared to the state-of-the-art results presented in the literature in different technologies: CMOS, glass, LCP and MEMS. The simulations are in good agreement with measurement, predicting the great potential of these inductors. The first 3D inductors using nanowire-vias presented inductances from 0.5 nH to 1.7 nH with small areas that range from 0.03 mm2 to 0.08 mm2.

Nanowire-based through substrate via for millimeter-wave frequencies

A new through substrate via for millimeter-wave frequencies is proposed. The via is formed by copper nanowires connecting the bottom to the top surfaces of a porous alumina membrane. It is shown here that the nanowire-via is simple to fabricate using only six low-cost processing steps. Its dimensions and spacing are only limited by the photolithography process, reaching small sizes, important for high-density interconnections. The nanowire-vias were tested as CPW transitions and characterized up to 40 GHz. The results show low insertion loss of less than 0.035 dB per transitions at 40 GHz.