Low DC Power Supply Research Articles

Carrier-Gas free arc igniter microplasma optical emission spectrometry for the determination of arsenic in soil

Rapid on-site assessment of arsenic contamination in soils is crucial for environmental protection and human health. In order to build an effective and affordable device for the determination of arsenic, the use of carrier gas supplies and high power energy consumption largely limit the miniaturization of microplasma-based optical emission spectrometry (OES). An arc igniter microplasma (AIM) can be powered by a low DC power supply and operated in the atmosphere of air without gas infusion, which is beneficial to construct a carrier-gas free and low power supply setup. Hydride generation (HG) can improve sample transport efficiency and reduce matrix effects, but the generated by-product hydrogen has not been explored as a sole working gas for plasma excitation. In this work, a hydride generation arc igniter microplasma optical emission spectrometer (HG-AIM-OES) was fabricated for detecting arsenic in soils. H2 derived from HG was served as a working gas to transport AsH3 to excite, eliminating the use of a carrier gas unit. Under the optimized operating conditions, the limit of detection (LOD) for arsenic was 164 μg/L (the analytical line at 234.98 nm), and good linearity of the method was achieved in the range of 0.5–20 mg/L with a precision of 3.14 % (the concentration of arsenic at 1 mg/L). In addition, the influence of H2 on AIM physical properties was carefully studied in the air and Ar discharge atmospheres. The accuracy of the proposed device was validated by the analysis of certified reference materials (CRMs) and a real soil sample, resulting in good agreement with the obtained results by air and Ar as working gas. This HG-AIM-OES system provides a miniaturized, carrier gas-free and low power consuming tool for monitoring and assessment of arsenic-contaminated soils.

High power density of AlGaAs/InGaAs doped-channelFETs with low DC power supply

High power density Al0.3Ga0.7As/In0.15Ga0.85As doped-channel FETs (modified DCFETs) biased at 3 V for 2.4 GHz wireless communication applications are proposed. A planar Si δ-doped layer is inserted inside the wide-bandgap undoped AlGaAs layer to reduce parasitic resistances and enhance the device microwave power performance. The modified DCFETs (M-DCFETs) exhibit an output power density of 302 mW/mm, a power-added efficiency of 52%, and a linear power gain of 19 dB under 2.4 GHz operation for a 1 mm gate-width device. These characteristics suggest that doped-channel FETs with a planar Si δ-doped layer can be used in high linearity and high power microwave device applications.

An ultracompact, 2-cc-size, low-power 2.5-Gb/s optical receiver module incorporating an MU receptacle

This paper describes an ultracompact, -3-V-supply, 2.5-Gb/s optical receiver module. For miniaturization of a gigabit-class receiver module, we used multichip configuration and bump technology, and we incorporated a miniature unit-coupling (MU) receptacle for small-size optical interface. To eliminate required external adjustment devices in the module for reduction of module size and assembling cost, we introduced new circuit techniques; the multistage automatic offset canceling technique is used for the postamplifier, and the sample-and-hold phase-locked loop (PLL) technique is employed for the clock and data recovery circuits. All the ICs were designed to operate at a low DC power supply of -3 V. The IC current was reduced by using 0.5-/spl mu/m Si bipolar process technology. The volume is only 2 cc (9/spl times/30.3/spl times/ 7.7 mm/sup 3/), including the MU receptacle. The experimental results show that the receiver has a wide dynamic range, from more than -2 to -19.4 dBm in optical input. These results were obtained without making any external adjustments. The module consumes a total power of 0.64 W.