Fractal capacitors

Abstract

A linear capacitor structure using fractal geometries is described. This capacitor exploits both lateral and vertical electric fields to increase the capacitance per unit area. Compared to standard parallel-plate capacitors, the parasitic bottomplate capacitance is reduced. Unlike conventional metal-to-metal capacitors, the capacitance density increases with technology scaling. A classic fractal structure is implemented with 0.6-m metal spacing, and a factor of 2.3 increase in the capacitance per unit area is observed. It is shown that capacitance boost factors in excess of ten may be possible as technology continues to scale. A computer-aided-design tool to automatically generate and analyze custom fractal layouts has been developed.

Low-voltage puzzle-like fractal microelectromechanial system variable capacitor suppressing pull-in

“…Recently, the authors in [1] presented fixed RF MEMS capacitors in the PolyMUMPS process (www.memscap.com) utilizing the concept of fractals [2]. The research attention in this paper is directed towards designing RF MEMS variable capacitors (MVC) using fractal geometries, and we focus on those that are actuated electrostatically.…”

CMOS RF integrated circuits at 5 GHz and beyond

“…Operation in the accumulation mode can be advantageous because of the lowered channel resistance that attends operation in this regime. As a result, large -frequency products (e.g., in excess of 100 GHz) are achievable with current processes, and continue to improve as technology scales [4].…”

5.8-GHz SUPPRESSED UWB BANDPASS FILTER EMPLOYING MODIFIED CRLH-TL OF TWO AND THREE UNIT CELLS

“…The capacitors are implemented by MIM structures which are with higher Q factor compared with the interdigital ones [9]. It therefore reduces the insertion loss of the CRLH bandpass filter.…”

“…In this paper, by proposing a modified CRLH unit cell with high rejection at 5.8 GHz, two novel bandpass filters for lower UWB band applications are designed and implemented using metal-insulator-metal (MIM) capacitors [9,10]. …”