Search

In this letter, we investigate the trade-off between parasitic capacitance and parasitic resistance of lattice-matched InP high-electron mobility transistors (HEMTs) with a double-recessed gate process. Lg = 80 nm HEMTs with and without SiO2 hardmask are used to adjust parasitic capacitance and parasitic resistance. And their DC and RF responses are measured and analyzed, such as the maximum transconductance (gm_max), ON-resistance (RON), current-gain cutoff frequency (fT), and maximum oscillation frequency (fmax). In order to obtain a high fmax, we adopt the technology of gate recess closer to the source electrode. The device with SiO2 hardmask, which has relatively smaller parasitic resistance, exhibits excellent characteristics of RON = 0.54 Ω·mm, gm_max = 1.087 S/mm, fT = 304 GHz, and fmax = 524 GHz. The device without the SiO2 hardmask achieved smaller drain output conductance (gds) and the ratio of gate-to-drain (Cgd) to gate-to-source (Cgs), resulting in a larger fmax of 690 GHz without significantly lowering fT (285 GHz). The HEMTs are providing more options for circuit processing. [ABSTRACT FROM AUTHOR]

A cross-band frequency hopping high power microwave (HPM) oscillator with permanent magnet package was proposed. The oscillator comprises of an inner Ku-band hollow oscillator and an outer C-band coaxial oscillator. By comparing with other cross-band HPM oscillators, this device is quite compact and high efficiency, for the guiding magnetic field is as low as 0.43 T, which is provided by a 74 kg permanent magnet. Since the cathode can be adjusted telescopically to produce annular electron beams at different radius, different bands HPMs can be generated in the inner and the outer slow wave structure. Verified by particle-in-cell simulation, a HPM with a frequency of 7.8 GHz and a power of 3.1 GW is achieved for C-band, corresponding to a power efficiency of 45%. Respectively, a Ku-band HPM output with a frequency of 14.4 GHz and a power of 1.3 GW were obtained, corresponding to a power efficiency of 45%. [ABSTRACT FROM AUTHOR]

10,11-Dehydrocurvularin is a natural benzenediol lactone (BDL) with a 12-membered macrolide fused to a resorcinol ring produced as a secondary metabolite by many fungi. In this review, we summarized the pieces of literature regarding biosynthesis, chemical synthesis, biological activities, and assumed work mechanisms of 10,11-dehydrocurvularin, which presented a potential for agricultural and pharmaceutical uses., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)