Fatima Salete Correra

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.

A modified Gummel-Poon model applied to HBTs

The Gummel-Poon model implemented in commercial simulators was modified to generate a large-signal model for HBTs. A representation of the thermal effects associated with the DC power dissipated by the device was added to the model and the forward transit time equation was adapted to account for the HBT transit time dependence on the base-collector voltage. The model was applied to a 1.5×20 ¿m2 AlGaAs/Gas and gave an adequate representation for the device DC characteristics for current densities up to 105 A/cm2, as well as bias-dependent S parameters up to 50 GHz. At 10 GHz the HBT output power at 1dB gain compression was predicted with less than 1dB error and the third order intercept point with less than 0.8 dB error, for class A and AB bias-points.

Parametric study of rectangular patch antenna using denim textile material

This paper presents a textile patch antenna designed for WBAN applications at 2.45 GHz ISM band. The antenna uses denim as substrate and conductive fabric for the ground plane and radiator layers. The main purpose of this paper is to analyze the influence of typical deviation of denim properties and patch radiator dimensions on the performance of the antenna. The parameters considered in the analysis are the relative permittivity and thickness of denim and the width and length of the rectangular patch radiator. The dependence of the central operation frequency of the antenna on those parameters was studied using the antenna reflection coefficient obtained from EM simulations. Rules of thumb for one-shot design were derived and applied to design a rectangular patch antenna. An antenna prototype was fabricated and measured, demonstrating a 10 dB impedance band of 4.8 % centered at 2.45 GHz, in good agreement with simulated results.

A design of a BPSK transmitter front end for ultra-wideband in 130nm CMOS

This paper presents a fully integrated BPSK (Binary Phase Shift Keying) Transmitter Front End for Ultra-Wideband (UWB) applications, designed in 130 nm CMOS technology. A simple architecture based on parallel pulse generator blocks in parallel is proposed to produce 9th derivative Gaussian pulses. In addition to the pulse generator, the circuit comprises a passive balun circuit, a common source amplifier, and a BPSK modulator. The transmitter has been simulated and the results demonstrated the circuit capability to operate as a front end BPSK transmitter. The proposed circuit generates output pulse envelopes of width 0.8 ns and maximum amplitude of 40 mVpp, an average power consumption of 1.9 μW/pulse and energy of 1.6 fJ/pulse when fed with a 715 MHz clock and 100 MHz data sources. The whole circuit occupies 480 × 320 μm2 (without pads). This pulse generator complies with FCC UWB spectral power mask).

A 2.488 Gb/s GaAs 1:4/1:16 demultiplexer IC with skip circuit for SONET STS-12/48 systems

A 1:4/1:16 demultiplexer IC with an integrated skip circuit has been successfully designed and fabricated employing SCFL standard cells based on 1 /spl mu/m MESFET foundry technology. The circuit was designed to operate at up to 2.5 Gb/s with low power dissipation. The demultiplexer employs a tree type architecture based on 1:2 demux blocks using tristage flip-flops. A new skip circuit without re-timing was proposed and integrated in the demultiplexer for frame alignment. The proposed skip circuit demonstrated its effectiveness and the IC operated either as a 1:4 or a 1:16 demultiplexer at up to 2.5 Gb/s with a power dissipation of 1 W. This IC is applicable for signal processing on SONET STS-12/48 optical communication systems.

ANALYSIS OF DIFFERENT PROBE GEOMETRIES FOR ETHANOL FUEL QUALIFICATION USING TIME-DOMAIN REFLECTOMETRY

This paper proposes sensors based on the time-domain reflectometry (TDR) technique for qualifying ethanol fuel. Four different probe geometries were proposed: bifilar, microstrip, coaxial, and helical. All probes allowed qualification of ethanol adulterated with water. Helical probe showed the best response. Thus, this proposal contributes to the development of electronic tongues.

An equivalent electrical circuit model for spiral and cross inductors on 0.35 µm CMOS technology

This paper presents a simple equivalent electrical circuit model to represent spiral and cross inductors on CMOS Technology. The inductors were designed and simulated using Momentum/ADS from Keysight, and were fabricated on AMS 0.35 µm CMOS technology. Simulation data was used to develop a RLC model for the inductors, where the reactive elements are constant and the resistance depends on frequency. A linear equation was proposed to represent the frequency dependence of the inductors resistance. The simulated results of spiral and cross inductors were in good agreement with the model results. On chip measurements of the inductors were performed from 1 to 10 GHz using a network analyzer. The inductance and maximum quality factor obtained from the measured data were well predicted by the proposed model, which showed good precision on spite of its simplicity.