Compact lowpass filter with a sharp roll‐off using patch resonators

Abstract

The ADI-FDTD can be used for efficient and stable electromagnetic modeling of the VLSI circuit as the time step is not restricted by the CFL stability condition. However, when the Berenger's PML is implemented in the ADI-FDTD method, this scheme will lead to late-time instability. In this article, we propose the modified PML conductivity profile to improve the stability of the ADI-FDTD with PML absorber. The multilevel crossover in VLSI circuit and RF inductor are studied. Compared to the conventional FDTD simulation, a significant reduction in calculation time can be achieved. Although the PML performance will be affected by the modified PML conductivity profile, it can be found that the simulation results are matched quite well with the reference results. The modified scheme can provide an efficient and accurate electromagnetic simulation method for VLSI circuits.

Planar elliptic function lowpass filter with sharp roll-off and wide stopband

“…As gap, g 1 increases, coupling between the resonant patches decreases, which increases the transmission zero frequency. The roll‐off rate, ξ of the lowpass filter is a measure of switching characteristics of the filter from passband to stopband, and is inversely proportional to the difference between the 3‐dB cutoff frequency and specified attenuation level frequency . Thus, by adjusting the position of the side resonators, we can modify the coupling between the patches of the resonators, which affect the roll‐off rate of the filter.…”

“…The slope of transition can be improved by introducing more number of reactive elements, which increases insertion loss in passband and layout area of the filter. Many different methods and topologies have been proposed recently to develop lowpass filter with excellent electrical characteristics utilizing (i) compact microstrip resonant cells with uniquely shaped defected ground structures , (ii) double equilateral U‐shaped defected ground structure , (iii) hexangular‐shaped resonator , (iv) symmetrical cascaded‐modified hairpin resonators , (v) stepped‐impedance hairpin units , (vi) stub‐loaded coupled‐line hairpin unit , (vii) open complimentary split ring resonator , (viii) symmetrically loaded multiple patch resonators on high impedance transmission line . Although these reported filters are good choice in modern communication systems, they suffer (i) additional radiation due to partially opened ground plane , (ii) poor roll‐off , and (iii) low stopband suppression level .…”

Design and Manufacturing of a Novel Compact 2.4 GHZ LPF Using a DGS-DMS Combination and Quasi Octagonal Resonators for Radar and GPS Applications

“…A compact LPF using embedded band-stop structure is proposed in [3]. In [4], another low-pass filter with sharp roll-off is proposed using cascaded multiple patch resonators, but only second harmonic suppression could be reached. Low-pass filters with microstrip coupled line hairpin units are demonstrated in [5,6] to achieve expanded stopband, but these filters suffer from low roll-off rate and high return loss in the stopband.…”

Ultra Sharp Transition-Band LPF with Miniaturized Size for GSM Applications

“…To increase the stop-band width, four stepped-impedance suppressors were adopted, even though this filter does not have a sharp cut-off and small size. A miniaturized LPF with gradual cut-off frequency and narrow stop-band using funnel-shaped resonator was reported in [6], so that four triangle resonators were utilized to increase the sharpness. A simple LPF using steppedimpedance resonators was presented in [7].…”