Compact band-rejected ultrawideband slot antennas inserting eith k/2 andk/4 resonators, ABSTRACT: A high-gain and low-noise micromachined CMOS distributed amplifier (DA) using cascaded gain cell, which constitutes an inductively parallel-peaking cascode-stage with a low-Q RLC load and an inductively series-peaking common-source stage, is demonstrated. Flat and high S 21 and flat and low noise figure (NF) are achieved simultaneously by adopting a slightly under-damped Q-factor for the second-order transconductance frequency response of the proposed cascaded gain cell. The two-stage DA consumes 37.8 mW and achieves flat and high S 21 of 20.47 6 0.72 dB with an average NF of only 3.3 dB over the 3$10 GHz band of interest, one of the best reported NF performances for a CMOS UWB DA or LNA in the literature. In addition, the result shows that a 0.84-dB increase in average S 21 (from 20.47 to 21.31 dB) and a 0.2-dB decrease (from 3.3 to 3.1 dB) in average NF are achieved mainly due to the improvement of the quality factor of the inductors in the DA. This means that this DA architecture in conjunction with the backside ICP dry-etching technique is very promising for high-performance 3$10 GHz UWB communication systems. ABSTRACT: In this article, a new configuration of higher selectivity bandpass filter using miniature open-loop stepped-impedance resonator (SIR) is designed and fabricated. The central frequency of the filter is 2.45 GHz and the bandwidth is 8%. Using miniature open-loop SIR resonator, we design filter based on cross-coupling and input and output external quality factor. A single transmission zero is realized by the cross-coupling in the structures, which can improve the skirt selectivity of the filter. The circuit size of a miniature open-loop SIR bandpass filter reduces to 50% of the square open-loop resonator bandpass filter. The results of measurements are in good agreement with the full-wave simulation results.

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In this paper, a new parallel-coupled-line microstrip band pass filter (BPF) improving the harmonic suppression performance of the second harmonic signal (2 , twice the passband frequency) is described. It is found that the desired passband performance is improved and the harmonic passband signal is diminished by enforcing the consecutive patterns in coupled-line and increasing the number of grooves to the optimum values. The recalculation of design parameters such as space-gap between lines, line widths and lengths is not required due to the simple modification of the conventional filter by inserting periodic patterns. To evaluate the validity of this novel technique, order-3 Butterworth BPF centered at 2.5 GHz with a 10% fractional bandwidth (FBW) and order-5 Chebyshev BPF centered at 10 GHz with a 15% FBW were used. When five and three square grooves are used, over 30-dB suppression at second harmonic signal is achieved in simulation and experiment. Finally, the comparison between the characteristics of filters with square and semicircular periodic grooves has been carried out by using the simulated results.

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In this letter, a structural modification technique of simple monopole to improve the input impedance bandwidth by using multiple staircased parasitic rings is suggested. In addition, the shape and size of parasitic rings are optimized to enhance the antenna bandwidth. The final optimized parameter values have been obtained from the parametric studies of the antenna and simple equation evaluating the resonant frequency. The electrical performances of the proposed antenna are verified in terms of the return loss and the radiation pattern by using commercially available softwares, CST MW Studio, and HFSS based on FDTD and FEM algorithms, respectively.