Search

Cooling is important for AlGaN/GaN high-electron mobility transistors (HEMTs) performance. In this paper, the advantages and disadvantages of the cooling performance of three cooling schemes: remote cooling (R-cool), near-chip cooling (NC-cool), and chip-embedded cooling (CE-cool) are compared. The influences of distinct geometric parameters and operating conditions on thermal resistance are investigated. The results show that the thermal resistances of NC-cool and CE-cool are almost the same as each other. Decreasing microchannel base thickness (hb) significantly increases the thermal resistance of CE-cool, and when its thickness is less than a critical value, NC-cool exhibits superior cooling performance than CE-cool. The critical thickness increases when decreasing the heat source pitch (Ph) and the convective heat transfer coefficient (hconv) or increasing the thermal conductivity of the substrate (λsub). Moreover, increasing Ph or λsub significantly improves the thermal resistance of three cooling schemes. Increasing hconv significantly decreases the thermal resistances of NC-cool and CE-cool while hardly affecting the thermal resistance of R-cool. The influence of the boundary thermal resistance (TBR) on the thermal resistance significantly increases at higher λsub and larger hconv. [ABSTRACT FROM AUTHOR]

This article presents an on-chip state-adjustable 8 GHz~12 GHz low-noise amplifier (LNA). It has two characteristics. First, an improved current reuse topology is proposed. By connecting a small capacitor in parallel with the drain of the first-stage transistor, the bandwidth is expanded and the in-band flatness is improved. Second, an innovative adaptive bias circuit is designed to cope with the influence of temperature and process on the performance of the amplifier, and a design method for on-chip adjustment of the chip state is proposed for the first time. As a result of these technologies, the chip area is 1.1 mm × 0.8 mm, the chip provides 24.4 dB nominal gain with merely 0.75 dB noise at 10 GHz, and yields 14.5 dBm output power at 1 dB compression point (OP1dB) when biased at 30 mA quiescent current, meanwhile, gain, OP1dB, and quiescent current can be adjusted on-chip. This design improves the comprehensive performance of X-band LNA and provides more flexibility for system engineers in application. The chip is fabricated using Win Semiconductors' 0.15 um InGaAs pHEMT E-mode process. [ABSTRACT FROM AUTHOR]

A novel water treatment process (designated E-Fe0-O 3 process) was constructed by combining electrolysis, micro-size zero valence iron (Fe0) and ozone in this study. Compared with other control processes, the combined process demonstrated a remarkable synergy, and it could obtain 90.5% of NB removal within 20 min. As for the mineralization experiment, the TOC removal efficiency for NB within 120 min was higher in the E-Fe0-O 3 process, while the energy consumption was lower than the traditional E-O 3 and E-Fe0 process. Interestingly, hydroxyl radicals (OH) acted as a key role for NB removal, and the concentration of OH in different processes were compared. Further study indicated OH, direct anode oxidation, direct ozonation, and zero valence iron catalysis were all responsible for nitrobenzene removal. Besides, the durability of Fe0 in the E-Fe0-O 3 process was systematically evaluated by reusing Fe0 10 times. Notably, the electric field could protect micro-size zero valence iron from passivation for catalytic ozonation after the long-term reaction. Finally, other ozone-refractory organics pollutants were also investigated in the E-Fe0-O 3 process, and the influence of various water matrices on NB removal was discussed. All results demonstrated that the E-Fe0-O 3 process was an efficient method to remove refractory organic pollutants in various natural waters. [Display omitted] • Combining electrolysis, Fe0, and O 3 achieves a remarkable synergy for nitrobenzene (NB) removal. • The E-Fe0-O 3 process can efficiently mineralize NB with low energy consumption. • Hydroxyl radical (OH) oxidation plays the dominant role in the E-Fe0-O 3 process. • The E-GAC-O 3 process obtains a stable removal efficiency of NB after recycling 10 times. • The applied electric field can protect Fe0 from passivation after long-term operation. [ABSTRACT FROM AUTHOR]

Cooling is important for AlGaN/GaN high-electron mobility transistors (HEMTs) performance. In this paper, the advantages and disadvantages of the cooling performance of three cooling schemes: remote cooling (R-cool), near-chip cooling (NC-cool), and chip-embedded cooling (CE-cool) are compared. The influences of distinct geometric parameters and operating conditions on thermal resistance are investigated. The results show that the thermal resistances of NC-cool and CE-cool are almost the same as each other. Decreasing microchannel base thickness ( h b ) significantly increases the thermal resistance of CE-cool, and when its thickness is less than a critical value, NC-cool exhibits superior cooling performance than CE-cool. The critical thickness increases when decreasing the heat source pitch ( P h ) and the convective heat transfer coefficient ( h conv ) or increasing the thermal conductivity of the substrate ( λ sub ). Moreover, increasing P h or λ sub significantly improves the thermal resistance of three cooling schemes. Increasing h conv significantly decreases the thermal resistances of NC-cool and CE-cool while hardly affecting the thermal resistance of R-cool. The influence of the boundary thermal resistance ( TBR ) on the thermal resistance significantly increases at higher λ sub and larger h conv .