Abstract:
Method for growing carbon nanotubes having a determined chirality, comprising the steps of fragmentation of at least one initial carbon nanotube (30) having a determined chirality with obtainment of at least two portions, or seeds, of carbon nanotube, each one having one free growth end (32); supply of atoms of carbon (33) with autocatalyst addition of the atoms of carbon (33) at the free end (32) of each portion of nanotube (30) to determine an elongation, or growth, of the nanotube (30).
Abstract:
A digital high-pass filter (12) has an input (IN), an output (OUT), and a subtractor stage (20), having a first input terminal, a second input terminal and an output terminal. The first input terminal of the subtractor stage (20) is connected to the input (IN) of the digital high-pass filter (12) and the output terminal is connected to the output (OUT) of the digital high-pass filter (12). A recursive circuit branch (21) is connected between the output (OUT) of the digital high-pass filter (12) and the second input terminal of the subtractor stage (20). Within the recursive circuit branch (21) are cascaded an accumulation stage (23), constituted by an integrator circuit, and a divider stage (24). The cutoff frequency (f t ) of the digital high-pass filter (12) is variable according to a dividing factor (den) of the divider stage (24).
Abstract:
Power semiconductor device (30) integrated on a semiconductor substrate (100) of a first type of conductivity comprising a plurality of elemental units, each elemental unit comprising a body region (40) of a second type of conductivity realised on a semiconductor layer (20) of the first type of conductivity formed on the semiconductor substrate (100), and a column region (50) of the first type of conductivity realised in said semiconductor layer (20) below the body region (40), wherein the semiconductor layer (20) comprises a plurality of semiconductor layers (21, 22, 23, 24), overlying each other, the resistivity of each layer being different from that of the other layers, and wherein said column region (50) comprises a plurality of doped sub-regions (51, 52, 53, 54), each realised in one of said semiconductor layers (21, 22, 23, 24), wherein the amount of charge of each doped sub-regions (51, 52, 53, 54) balances the amount of charge of the semiconductor layer (21, 22, 23, 24).
Abstract:
Both a chalcogenide select device (24, 120) and a chalcogenide memory element (40, 130) are formed within vias within dielectrics (18, 22). As a result, the chalcogenides is effectively trapped within the vias and no glue or adhesion layer is needed. Moreover, delamination problems are avoided. A lance material (30) is formed within the same via (31) with the memory element (40, 130). In one embodiment, the lance material is made thinner by virtue of the presence of a sidewall spacer (28); in another embodiment no sidewall spacer is utilized. A relatively small area of contact between the chalcogenide (40) used to form a memory element (130) and the lance material (30) is achieved by providing a pin hole opening in a dielectric (34), which separates the chalcogenide and the lance material.
Abstract:
In order to execute, as a function of a received signal (r), a procedure of channel estimation in a transmission channel with memory in a telecommunications system, there is envisaged an operation of estimation of a delay spread associated to said channel, said operation of estimation comprising calculation of a root mean square value ( τ rms ) of delay spread by means of a step of evaluation of crossings with a threshold level of a quantity associated to a transfer function of said channel. Said step of evaluation of crossings comprises evaluating a mean number of crossings ( λ 0 ) of the real and imaginary parts of said channel transfer function with a threshold level corresponding to the zero level. Preferential application is to OFDM telecommunications systems and in particular wireless. systems according to the IEEE 802.11a WLAN standard or the Hyperlanil WLAN standard.
Abstract:
L'invention concerne un processeur d'exécution d'un algorithme Rijndeal, effectuant plusieurs tours de chiffrement d'une matrice composée de blocs de données pour obtenir une matrice de même taille, chaque tour impliquant une matrice de blocs de clés et une table de substitution des blocs de données, le processeur comportant : un premier registre d'entrée (102) pour contenir une colonne de blocs de données d'entrée ; un registre de sortie (111) pour contenir une colonne de blocs de données de sortie ou une colonne de blocs intermédiaires ; un deuxième registre d'entrée (101) pour contenir une colonne de blocs de clés ou les blocs de données intermédiaires ; un élément (104) de substitution de blocs recevant les données bloc par bloc après sélection (103) dans le premier registre et fournissant, pour chaque bloc, une colonne de blocs ; un élément (109) de permutation circulaire des blocs de la colonne du circuit de substitution ; et un élément (110) de combinaison OU-Exclusif de la colonne de blocs du circuit de permutation avec le contenu du deuxième registre, le résultat de la combinaison étant chargée dans le registre de sortie.
Abstract:
A process for the fabrication of an integrated device in a semiconductor chip envisages: forming a semiconductor layer (5') partially suspended above a semiconductor substrate (2) and constrained to the substrate (2) by temporary anchorages (10, 15'); dividing the layer (5') into a plurality of portions (13) laterally separated from one another; and removing the temporary anchorages (10, 15'; 38), in order to free the portions (13).
Abstract:
A power device (1) formed by a thyristor (25) and by a MOSFET transistor (26), series-connected between a first and a second current-conduction terminal (A, S). the power device (1) moreover has a control terminal (G) connected to an insulated-gate electrode (20) of the MOSFET transistor (26) and receiving a control voltage for turning on/off the device, and a third current-conduction terminal (B) connected to the thyristor (25) for fast extraction of charges during turning-off. Thereby, upon turning off, there are no current tails, and turning off is very fast. The power device does not have parasitic components and consequently has a very high reversebias safe-operating area (RBSOA).
Abstract:
A device for maintaining fine alignment between an incoming spread spectrum signal and a locally generated code in a digital communication receiver comprises: - a delay line (56) for storing a plurality of consecutive samples (E-1, E, M, L, L+1) of the incoming spread spectrum signal; - three digitally controlled interpolators (24, 26, 28) for determining by interpolation between consecutive samples an interpolated early sample (e), an interpolated middle sample (m) and an interpolated late sample (1); - two correlators (30, 32) for calculating an error signal (ξ) as the difference between the energy of the symbols computed from the interpolated early (e) and late (1) samples; - a circuit for generating a control signal (S¿OUT?) for controlling the interpolation phase of the digitally controlled interpolator (24) for the early sample (e), and - a digital non-linear filter (68), for smoothing the control signal (S¿OUT?) of the interpolator (24) for the early sample (e), enabling the update operation of the control signal only when the absolute value (|ξ(n)|) of the error signal at a time instant n is smaller than the absolute value (|ξ(n-1)|) of the same error signal at a time instant n-1.
Abstract:
The circuit comprises a differential amplifier (10) with two inputs and two outputs and a common mode regulation circuit. Between a regulation terminal (INCM) of the amplifier and the outputs there are connected a first (C1p) and a second (1m) capacitor and first (C3) and second (C4) capacitive means that by means of controlled switches (SW9-SW12) can be alternatively and simultaneousy connected in parallel with, respectively, the first ((C1p) and the second (C1m) capacitor or between a first (VB) and a second (Vref1) reference voltage terminal. The capacitances C3 and C4 may be different in value such as to satisfy the following equality: Vcmn = Vref1 + '(Vrefp-Vrefm)/2!* (C4-C3)/(C3+C4), where Vcmn is the desired common mode output voltage, Vrefp and Vrefm are the differential output voltages and Vref1 is the voltage of the second reference terminal.are chosen in such a way as to satisfy the following equality : Vcmn = Vref1 + [(Vrefp-Vrefm)/2] * (C4-C3)/(C3+C4), where Vcmn is the desired common mode output voltage, Vrefp and Vrefm are the differential output voltages and Vref1 is the voltage of the second reference terminal.