Narrow Results

We analyze steady-state and transient electron transport in the group III-nitride materials at high and ultra-high electric fields for different electron concentration regimes. At high electron concentrations where the electron distribution function assumes a shifted Maxwellian, we investigate different time-dependent transient transport regimes through the phase-plane anyalysis. Unexpected electron heating pattern is observed during the velocity overshoot process with a moderate electron temperature near the peak velocity followed by rapid increase in the deceleration period. For short nitride diodes, space-charge limited transport is considered by taking into account the self-consistent field. In this case, the overshoot is weaker and the electron heating in the region of the peak velocity is greater than that found for time-dependent problem. The transient processes are extended to sufficiently larger distances as well. When the electron concentration is small, we propose a model which accounts the main features of injected electrons in a short device with high fields. The electron velocity distribution over the device is found as a function of the field. It is demonstrated that in high fields the electrons are characterized by the extreme distribution function with the population inversion.

To suppress the inrush current and overshoot voltage generated at the start-up stage of Buck–Boost converter, a digital–controlled soft-start circuit based on digital-to-analog converter (DAC) control technology is proposed in this paper. The power consumption of the circuit is zero and the circuit is also keeps the characteristics of simple structure and high reliability. The circuit has been integrated into a Buck–Boost converter with negative voltage output by using the 0.18$\mu$m CDMOS high voltage process. The experimental results show that this circuit can effectively suppress the rush current, and the output voltage drops smoothly from 0 to the adjustment value, $-4$V.

The dual formulation of the maximal-minimal problem for an objective function of the error response to a fixed input in the continuous-time systems is given by a result of Fenchel dual. This formulation probably changes the original problem in the infinite dimensional space into the maximal problem with some restrained conditions in the finite dimensional space, which can be researched by finite dimensional space theory. When the objective function is given by the norm of the error response, the maximum of the error response or minimum of the error response, the dual formulation for the problems of L¹-optimal control, the minimum of maximal error response, and the minimal overshoot etc. can be obtained, which gives a method for studying these problems.

This paper introduces an accurate analysis of time domain response of carbon nanotube (CNT) interconnects based on distributed RLC model that takes the effect of both the series resistance and the output parasitic capacitance of the driver into account. Using rigorous principle calculations, accurate expressions for the transfer function of these lines and their time domain response have been presented. It has been shown that the second-order transfer function cannot represent the distributed behavior of the long CNT interconnects, and the fourth-order approximation offers a better result. Also, the time response of a driven long CNT interconnect versus length and diameter have been studied. The obtained results show that the overshoot increases and the time delay decreases with increasing the CNT diameter, such that with the diameter value of 10 nm for a 3.3 mm CNT interconnect, the maximum overshoot value reaches about 95% of the amplitude of the driver input. On the contrary, the overshoot increases and the time delay decreases with decreasing the length of the CNT, such that with the length value of 1 mm for a 5 nm diameter CNT interconnect, the maximum overshoot reaches about 90% of the amplitude of the driver input.

We analyze steady-state and transient electron transport in the group III-nitride materials at high and ultra-high electric fields for different electron concentration regimes. At high electron concentrations where the electron distribution function assumes a shifted Maxwellian, we investigate different time-dependent transient transport regimes through the phase-plane anyalysis. Unexpected electron heating pattern is observed during the velocity overshoot process with a moderate electron temperature near the peak velocity followed by rapid increase in the deceleration period. For short nitride diodes, spacecharge limited transport is considered by taking into account the self-consistent field. In this case, the overshoot is weaker and the electron heating in the region of the peak velocity is greater than that found for time-dependent problem. The transient processes are extended to sufficiently larger distances as well. When the electron concentration is small, we propose a model which accounts the main features of injected electrons in a short device with high fields. The electron velocity distribution over the device is found as a function of the field. It is demonstrated that in high fields the electrons are characterized by the extreme distribution function with the population inversion.