Eyad Arabi

Tunable Bandpass Filter Based on Partially Magnetized Ferrite LTCC With Embedded Windings for SoP Applications

Tunable filters that are based on ferrite materials often require large and bulky electromagnets. In this work, we present a tunable filter in the Ku-band, which is realized in multilayer ferrite LTCC substrate with embedded bias windings, thus negating the need of a large electromagnet. Also, because of the embedded windings, the bias fields are not lost at the air-substrate interface and therefore the field and current requirements are reduced by an order of magnitude as compared to the previously reported filters. A simulation strategy that uses full permeability tensor with arbitrarily directed magnetic fields has been used to model the filter on a partially magnetized ferrite substrate. Special attention has also been paid to approximate the non-uniform magneto-static fields produced by the embedded windings. The complete design is implemented in 10 layers of ferrite LTCC, making it the first magnetically tunable filter with embedded windings and extremely small size [(5 × 5 × 1.1) mm3]. The filter demonstrates a measured tunability of 4% and an insertion loss of 2.3 dB. With the small form factor, embedded windings, and low bias requirements, the design is highly suitable for compact and tunable SoP applications.

A 3-D Miniaturized High Selectivity Bandpass Filter in LTCC Technology

Transmission zeros are used to improve the roll-off factors of filters but as a consequence, the out-of-band rejection decreases. In this work, an LTCC filter design is presented which employs a series inductor (implemented as a via hole) to improve the out-of-band rejection by introducing a third transmission zero. The filter, designed for GPS band (1.57 GHz), has one of the smallest reported foot prints ( (0.063×0.048×0.005)λg) and demonstrates the highest roll off factor (16.7 dB/100 MHz) for this band. With only four LTCC layers, the design is cost effective and thus highly suitable for miniaturized, ultra-thin system-on-package applications.

The Effect of Self-Heating on the Performance of a Tunable Filter With Embedded Windings in a Ferrite LTCC Package

Traditionally, ferrite-based tunable filters are biased by large and bulky electromagnets, which require high currents to overcome the dissipated fields at the air interface between the electromagnet and the ferrite substrate. This problem has been solved by implementing the windings inside the package using ferrite low-temperature co-fired ceramic (LTCC). However, these embedded windings, which are densely packed, generate heat that affects the characteristics of the ferrite material. In this paper, we investigated the heat effects due to embedded windings in ferrite LTCC filters. We also incorporated the heating effects into an electromagnetic simulation model and achieved a good agreement between the simulations and the measurements. We found that increasing the temperature of the filter module from 0 °C to 190 °C by external heating causes the center frequency of the filter to shift by about 1 GHz. Alternatively, when a dc current is passed through the bias windings, heat is generated in the windings to a temperature of 250 °C measured at 260 mA of current. This heat causes the tunability of the filter to increase by more than 2%.

Tunable, concurrent multiband, single chain radio architecture for low energy 5G-RANs

This invited paper considers a key next step in the design of radio architectures aimed at supporting low energy consumption in 5G heterogeneous radio access networks. State-of-the-art mobile radios usually require one RF transceiver per standard, each working separately at any given time. Software defined radios, while spanning a wide range of standards and frequency bands, also work separately at any specific time. In 5G radio access networks, where continuous, multiband connectivity is envisaged, this conventional radio architecture results in high network power consumption. In this paper, we propose the novel concept of a concurrent multiband frequency-agile radio (CM-FARAD) architecture, which simultaneously supports multiple standards and frequency bands using a single, tunable transceiver. We discuss the subsystem radio design approaches for enabling the CM-FARAD architecture, including antennas, power amplifiers, low noise amplifiers and analogue to digital converters. A working prototype of a dual-band CM-FARAD test-bed is also presented together with measured salient performance characteristics.

Analytical Formulas for the Coverage of Tunable Matching Networks for Reconfigurable Applications

Tunable matching networks (MNs) are essential components for agile radio frequency systems. To optimally design such networks, the total area they cover on the Smith chart needs to be determined. In this paper, the coverage areas of typical MNs have been determined analytically for the first time. It has been found that the coverage area is encompassed by up to five arcs. Analytical expressions for the centers and radii for these arcs have been derived. The theoretical analysis is provided for four typical MNs and verified by circuit simulation and measured data. Moreover, a dynamically load-modulated power amplifier has been designed using the presented theoretical techniques, which demonstrates a measured improvement in the power added efficiency of up to 5% in the frequency range of (0.8–0.9) GHz.

A planar and tunable bandpass filter on a ferrite substrate with integrated windings

Tunable Filters that are based on ferrite materials are often biased by external magnets or coils which are large and bulky. In this work a completely planar, CPW-based bandpass filter is presented with integrated windings. Due to these windings the size of the filter is only 26mm × 34mm × 0.38mm which is orders of magnitude smaller than the traditional designs with external windings. The filter is realized by electroplating of Copper over seed layers of Titanium and Gold over a YIG substrate. The fabricated filter achieves a tunability of 3.4% without any external magnets or coils. A good insertion loss of 2.3 dBs and rejection greater than 50 dBs have been obtained. To the best of the authors knowledge, this design is the first ferrite-based design that is completely planar and self-biased.

Analysis of the coverage of tunable matching networks with three tunable elements

Tunable matching networks are crucial for agile radio frequency circuits. To optimally design such networks the overall coverage needs to be determined. In this work, analytical formulas for the coverage area within the Smith chart of a three-element tunable-network are derived. It has been found that up to sixteen circles bound the coverage area. Analytical expressions for the centers and radii of these circles have been derived and verified by circuit simulation as well as measured data. The formulas in this work can be readily integrated into CAD tools, thus provide a valuable tool for the design of tunable circuits.

Design of a triple-band power amplifier using a genetic algorithm and the continuous mode method

Dual band power amplifiers use either large and lossy matching networks, or switches, which do not allow concurrent operation. In this work, a concurrent, triple-band power amplifier with a simple matching network is presented. The theory of continuous modes of operation has been used in the optimization of the input and output matching networks using a genetic algorithm. As proof of concept, a design at 0.8, 1.8, and 2.4 GHz has been fabricated and characterized in the laboratory. A maximum power added efficiency and output power of 70% and 41 dBm have been achieved using our novel design. The design described in this paper is based on a solid theoretical analysis and demonstrates a simplified biasing network. Such design is highly suitable for next generation wireless systems with aggregated carriers.

2017 IEEE Topical Conference on RF/Microwave Power Amplifiers for Radio and Wireless Applications (PAWR 2017)

Dual band power amplifiers use either large and lossy matching networks, or switches, which do not allow concurrent operation. In this work, a concurrent, triple-band power amplifier with a simple matching network is presented. The theory of continuous modes of operation has been used in the optimization of the input and output matching networks using a genetic algorithm. As proof of concept, a design at 0.8, 1.8, and 2.4 GHz has been fabricated and characterized in the laboratory. A maximum power added efficiency and output power of 70% and 41 dBm have been achieved using our novel design. The design described in this paper is based on a solid theoretical analysis and demonstrates a simplified biasing network. Such design is highly suitable for next generation wireless systems with aggregated carriers.