NQS

About: NQS is a research topic. Over the lifetime, 337 publications have been published within this topic receiving 4226 citations.

A charge-controlled model for MOS transistors

Abstract: As MOS (metal-oxide-semiconductor) devices scale to submicron lengths, short-channel effects begin to dominate device behavior, and designers of VLSI (very-large-scale-integrated) circuits see an improved transistor model as a necessary tool. A new physically based, charge-controlled model for the DC current, the intrinsic terminal charges, and the transcapacitances in the MOS transistor under quasistatic conditions has been developed. The model expresses the current in the MOS transistor in terms of the mobile charge per unit area in the channel, and uses a complete set of natural units for velocity, voltage, length, charge, and current. The current-flow equation for the transistor includes both a drift term and a diffusion term, so that the formulation applies equally over the subthreshold, saturation, and "ohmic" regions of transistor operation and includes the effect of velocity saturation. The solution of this dimensionless current-flow equation using these units is a simple, continuous expression, and is suitable for the computer simulation of integrated circuits. The expression allows the regimes of transistor operation and the behavior of long-channel devices versus short-channel devices to be discerned easily. In particular, the expressions for source and drain terminal charges combine the mobile charge in the channel at the source and drain ends in simple polynomials. Analysis of the model shows a fundamental relation between the transistor transcapacitances and transconductances, and permits the development of efficient simulation models of them. Our physically based transistor model uses parameters derived from the fabrication process by direct measurement and from the dimensions of the device. The zero-order model agrees closely with measurements on the scaling of current with channel length down to submicron channel lengths. For more detailed analog simulations, the model contains several first-order effects calculated as perturbations on the simple model. Comparisons among calculated and measured curves of conductance, capacitance, and drain currents demonstrate the accuracy of the model both above the below threshold for a number of experimental devices of different channel lengths. Results from the model concur with measurements on short-channel transistors down to 0.6-micron channel length. Several analog circuit simulators now contain the model.

Development and Validation of Spectrophotometric Method for Determination of Finasteride in Pharmaceutical Formulation Using 1,2-Naphthoquine-4-sulfonate (NQS)

Abstract: A rapid, simple and sensitive method for the determination of finasteride using sodium 1,2-naphthoquine-4- sulfonate (NQS) has been developed. The method is based on the fact that a brown product can be formed by the reaction between finasteride and sodium NQS in a buffer solution of a pH 13.0. Beer’s law is obeyed in the range 2-14 μg/ml of finasteride at maximum wavelength of 447 nm. The linear regression equation of the calibration curve is y=0.062857x+0.069857, with a linear regression correlation coefficient of 0.999. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.03 and 0.09 μg/ml, respectively. The method has been successfully applied to the determination of finasteride in pharmaceutical formulation. The results were in good agreement with those obtained with the official high performance liquid chromatography (HPLC) method. The proposed method is useful for routine analysis of finasteride in quality control laboratories.

Non‐quaternary suppression with flip‐back: A useful technique for high‐resolution NMR of solids

Abstract: A modification to the well-established non-quaternary suppression pulse sequence used in high-resolution solid-state NMR is proposed which allows the inclusion of a ‘flip-back’ pulse. The utility of such a sequence is demonstrated by spectra obtained using the standard and modified NQS sequences for a glycidyl ether derivative.

Nonquasi-Static Charge Model for Common Double-Gate MOSFETs Adapted to Gate Oxide Thickness Asymmetry

Abstract: With the unique quasi-linear relationship between the surface potentials along the channel, recently we have proposed a quasi-static terminal charge model for common double-gate MOSFETs, which might have asymmetric gate oxide thickness. In this brief, we extend this concept to develop the nonquasi-static (NQS) charge model for the same by solving the governing continuity equations. The proposed NQS model shows good agreement against TCAD simulations and appears to be useful for efficient circuit simulation.