The main objective of this study is to develop a near-infrared (NIR) tunable external cavity laser (ECL) that is based on a semiconductor optical amplifier and two different wavelength selective elements. In order to achieve the wavelength selection, several filters have been tested in the ECL setups, including plasmonic filter, acoustooptic tunable filter (AOTF), gradient photonic crystal and ...

In this paper, frequency-tunable microstrip antennas, for cognitive radio applications, are proposed. The approach is based on electrically tuning the antenna’s operating frequency by integrating reconfigurable band pass filters into wideband antenna structures. The design of an open loop resonator (OLR)-based bandstop filter, and its transformation to a bandpass filter, are investigated first....

We report on a wavelength-tunable filter based on multimode interference (MMI) effects. A typical MMI filter consists of a multimode fiber (MMF) spliced between two single-mode fibers (SMF). The peak wavelength response of the filter exhibits a linear dependence when the length of the MMF is modified. Therefore a capillary tube filled with refractive-index-matching liquid is used to effectively...

Introduction: Optically realised microwave filters offer advantages such as large operating bandwidth and immunity to microwave interference. Several researchers have investigated microwave photonic filters to enable tunable and reconfigurable systems. Capmany et al. [1] proposed a filter system that employs an array of tunable lasers. The filter can be both tuned and reconfigured by changing t...

The effect of filter parameters on the phase noise of RF MEMS tunable filters employing shunt capacitive switches is investigated in this article. It is shown that the phase noise of a tunable filter is dependent on the input power, fractional bandwidth, filter order, resonator quality factor, and tuning state. Phase noise is higher for filters with smaller fractional bandwidth. In filters with...

This paper proposes the design of a tunable radiofrequency filter based on the switched capacitor techniques. This circuit, which can replace high-Q external passive filters, allows a high selectivity with a tunable center frequency range of 400 MHz [700-1100 MHz], with quality factor up than 1100. Implemented in 0.18 μm CMOS technology, this circuit is intended to be used for the next generati...

This paper presents a design and performance analysis of tunable RF front end circuits such as RF band pass filter and VCO for multiband applications. The tunable element is an active inductor, built by MOS transistors. It is attractive due to its tunable and larger inductance values. The RF band pass filter is realized using active inductor with suitable input and output buffer stages. The tun...

Traveling Wave Tubes (TWTs) consist of different elements. The most important element of TWT is the RF circuit. RF circuits in helix TWTs need a dielectric support to hold the helix; this support also has an effect in electromagnetic properties of RF circuits. A novel dielectric support is proposed to reduce the second harmonic of helix TWTs. The dielectric support in this structure consists of...

We show that an all-fiber acousto-optic tunable filter based on polarization mode coupling using torsional acoustic wave is immune to the fiber bend and physical contact in the acousto-optic interaction region. We also propose and demonstrate a novel strain-free and size-reduced tunable filter with a 4-m-long fiber acousto-optic interaction region looped into a 5- cm-diameter coil.

In this paper, design of a CMOS tunable versatile filter using current conveyor (CC) is presented. The filter is realized at the same time as on the chip is tunable for low pass, band pass, high pass, and elliptical notch filter. The circuit is utilizes two current conveyors, one Operational Trans-conductance Amplifier (OTA), four resistors and two grounded capacitors, ideal for integration. It...