Search

A 6.0–13.5 GHz alias-locked loop (ALL) frequency synthesizer is designed and simulated in 130 nm CMOS. Using an aliasing divider, the ALL architecture makes it possible to create high-speed frequency synthesis circuits without relying on a traditional divider clocked at fVCO in the feedback path. In this implementation, a new architecture of high frequency ring oscillator is proposed with a feedforward path and selectable modes of operation for different frequency ranges. This ring oscillator provides both a high oscillating frequency and a wide tuning range. Simulation results have shown that the design synthesizes the desired frequencies and consumes 30.01 mW @ 13.0 GHz with a 1.2 V power supply. [ABSTRACT FROM AUTHOR]

In this article we report a study of in situ polymerization of ethylene by intercalated montmorillonite (MMT) with metallocene, allowing an investigation of the nanoscopic confinement effect of olefin polymerization and of the structure of polymer prepared in situ. Ethylene polymerization by intercalated MMT with metallocene and the varied aggregation morphology of the resulting polymer during polymerization were studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC), and gel permeation chromatography (GPC). The polymerization kinetics and the resulting polymer before and after destruction of the silicate registry were different. The laminated structure of silicate lowered the all-reaction rate, including the propagation, chain transfer, and termination reactions, producing polymer of a high molecular weight. Moreover, the melting point of the polymer gradually increased during the in situ polymerization, indicating that nanoscopic confinement between solid surfaces affects the crystallization behavior of polyethylene via in situ polymerization. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 38–43, 2004