Current Issue : October - December Volume : 2014 Issue Number : 4 Articles : 6 Articles
A low-power wideband mixer is designed and implemented in 0.13 ????m standard CMOS technology based on resistive feedback\ncurrent-reuse (RFCR) configuration for the application of cognitive radio receiver. The proposed RFCR architecture incorporates\nan inductive peaking technique to compensate for gain roll-off at high frequencywhile enhancing the bandwidth.Acomplementary\ncurrent-reuse technique is used between transconductance and IF stages to boost the conversion gain without additional power\nconsumption by reusing the DC bias current of the LO stage. This downconversion double-balanced mixer exhibits a high and\nflat conversion gain (CG) of 14.9 �± 1.4 dB and a noise figure (NF) better than 12.8 dB.The maximum input 1-dB compression point\n(P1dB) andmaximum input third-order intercept point (IIP3) are ?13.6 dBmand ?4.5 dBm, respectively, over the desired frequency\nranging from 50 MHz to 10GHz.The proposed circuit operates down to a supply headroom of 1V with a low-power consumption\nof 3.5 mW....
In PV applications, under mismatching conditions, it is necessary to adopt a maximum power point tracking (MPPT) technique\nwhich is able to regulate not only the voltages of the PV modules of the array but also the DC input voltage of the inverter. Such\na technique can be considered a hybrid MPPT (HMPPT) technique since it is neither only distributed on the PV modules of the\nPV array or only centralized at the input of the inverter. In this paper a new HMPPT technique is presented and discussed. Its\nmain advantages are the high MPPT efficiency and the high speed of tracking which are obtained by means of a fast estimate of\nthe optimal values of PV modules voltages and of the input inverter voltage.The new HMPPT technique is compared with simple\nHMPPT techniques based on the scan of the power versus voltage inverter input characteristic. The theoretical analysis and the\nresults of numerical simulations are widely discussed. Moreover, a laboratory test system, equipped with PV emulators, has been\nrealized and used in order to experimentally validate the proposed technique....
A wide interest has been observed to find a low power and area efficient hardware design of discrete cosine transform (DCT)\nalgorithm. This research work proposed a novel Common Subexpression Elimination (CSE) based pipelined architecture for DCT,\naimed at reproducing the cost metrics of power and area while maintaining high speed and accuracy in DCT applications. The\nproposed design combines the techniques of Canonical Signed Digit (CSD) representation and CSE to implement the multiplierless\nmethod for fixed constant multiplication of DCT coefficients. Furthermore, symmetry in the DCT coefficient matrix is used\nwith CSE to further decrease the number of arithmetic operations. This architecture needs a single-port memory to feed the\ninputs instead of multiport memory, which leads to reduction of the hardware cost and area. From the analysis of experimental\nresults and performance comparisons, it is observed that the proposed scheme uses minimum logic utilizing mere 340 slices and\n22 adders. Moreover, this design meets the real time constraints of different video/image coders and peak-signal-to-noise-ratio\n(PSNR) requirements. Furthermore, the proposed technique has significant advantages over recentwell-known methods along with\naccuracy in terms of power reduction, silicon area usage, and maximum operating frequency by 41%, 15%, and 15%, respectively....
This work presents the design of a low power upconversion mixer adapted in medical remote sensing such as wireless endoscopy\napplication. The proposed upconversion mixer operates in ISMband of 433MHz.With the carrier power of ?5 dBm, the proposed\nmixer has an output inferred 1 dB compression point of ?0.5 dBm with a corresponding output third-order intercept point (OIP3)\nof 7.1 dBm.The design of the upconversion mixer is realized on CMOS 0.13 ????m platform, with a current consumption of 594 ????A at\nsupply voltage headroom of 1.2V....
The design of monitoring and predictive alarm systems is necessary for successful overhead power transmission line icing. Given\nthe characteristics of complexity, nonlinearity, and fitfulness in the line icing process, a model based on a multivariable time series\nis presented here to predict the icing load of a transmission line. In this model, the time effects of micrometeorology parameters\nfor the icing process have been analyzed. The phase-space reconstruction theory and machine learning method were then applied\nto establish the prediction model, which fully utilized the history of multivariable time series data in local monitoring systems to\nrepresent the mapping relationship between icing load and micrometeorology factors. Relevant to the characteristic of fitfulness\nin line icing, the simulations were carried out during the same icing process or different process to test the model�s prediction\nprecision and robustness. According to the simulation results for the Tao-Luo-Xiong Transmission Line, this model demonstrates\na good accuracy of prediction in different process, if the prediction length is less than two hours, and would be helpful for power\ngrid departments when deciding to take action in advance to address potential icing disasters....
The effect analysis of strain rate on power transmission tower-line system under seismic excitation is studied in this paper. A threedimensional\nfinite element model of a transmission tower-line system is created based on a real project. Using theoretical analysis\nand numerical simulation, incremental dynamic analysis of the power transmission tower-line system is conducted to investigate\nthe effect of strain rate on the nonlinear responses of the transmission tower and line.The results show that the effect of strain rate\non the transmission tower generally decreases the maximum top displacements, but it would increase the maximum base shear\nforces, and thus it is necessary to consider the effect of strain rate on the seismic analysis of the transmission tower. The effect\nof strain rate could be ignored for the seismic analysis of the conductors and ground lines, but the responses of the ground lines\nconsidering strain rate effect are larger than those of the conductors.The results could provide a reference for the seismic design of\nthe transmission tower-line system....
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