Abstract:
A bipolar transistor with very high dynamic performance, usable in an integrated circuit. The bipolar transistor has a single-crystal silicon emitter region with a thickness smaller than 50 nm. The base of the bipolar transistor is made of an SiGe alloy.
Abstract:
A method of synchronizing a substantially rectilinear signal being propagated through an unknown channel, in the presence of unknown substantially rectilinear interferences, received by an array of N sensors, in which a known training sequence s(nT) is used comprising K symbols and sampled at the symbol rate T (s(nT), 0≦n≦{tilde over (K)}1), characterized in that, based on observations x((n+l/p)T) over the duration of the training sequence, where p=T/Te is an integer and Te the sampling period, a virtual observation vector X((n+l/p)T)=[x((n+l/p)T)T, x((n+l/p)T)†]T is defined, as well as a decision criterion or decision statistic taking into account the second-order non-circular nature of the interferences, by using the first and second correlation matrices of the virtual observation vector X((n+l/p)T).
Abstract:
A bipolar transistor having a base region resting by its lower surface on a collector region and surrounded with a first insulating layer, a base contact conductive region in contact with an external upper peripheral region of the base region, a second insulating region in contact with an intermediary upper peripheral region of the base region, an emitter region in contact with the central portion of the base region. The level of the central portion is higher than the level of the intermediary portion.
Abstract:
A method forms a bipolar transistor in a semiconductor substrate of a first conductivity type. The method includes: forming on the substrate a single-crystal silicon-germanium layer; forming a heavily-doped single-crystal silicon layer of a second conductivity type; forming a silicon oxide layer; opening a window in the silicon oxide and silicon layers; forming on the walls of the window a silicon nitride spacer; removing the silicon-germanium layer from the bottom of the window; forming in the cavity resulting from the previous removal a heavily-doped single-crystal semiconductor layer of the second conductivity type; and forming in said window the emitter of the transistor.
Abstract:
A method for estimating one or more parameters of a propagation channel, with a priori knowledge of at least one signal, in a system having one or more sensors. The method includes correlating one or more signals received by the sensors with the known signal, sampling the received signals at a sampling period and selecting a number of samples per concatenation, and determining at least one parameter of the propagation channel which enables the most efficient reconstruction of the signals via a maximum likelihood method.
Abstract:
A method and apparatus for spatial multiplexing and demultiplexing of radio signals. A multichannel transmitter and receiver is integrated in a base station and coupled to an antenna array. Using digital radio signals containing previously known or non-Gaussian sequences and arranged in frames, the spatial information about each mobile unit is estimated on the basis of the signal received by the receiver for the reception and transmission frequencies. This is done by known sequences or by blind source separation methods. The respective paths of each mobile unit with the power above a predetermined threshold is isolated by spatial filtering in the presence of multiple channel paths in order to provide spatial demultiplexing. Simultaneously, the intended signal is transmitted in the direction of the main path of each mobile unit while protecting each mobile unit from signals transmitted in the direction of other mobile units by spatial filtering with cancelling constraints in order to provide spatial multiplexing.
Abstract:
The process according to the invention consists, in order to reduce the number of coefficients of the filters of the spatial part and the temporal part connected to the output of the spatial part, in jointly adapting the coefficients of the filters of each part using an adaptive algorithm according to the paths selected on the basis of a determined criterion. The coefficients are periodically recalculated at the rate of the known symbols in the learning sequences in order to minimize the estimation error apparent between a response signal (d(t)) and the receiver output signal (z(t)).
Abstract:
Method of high-resolution direction finding to an arbitrary even order, 2q (q>2), for an array comprising N narrowband antennas each receiving the contribution from P sources characterized in that the algebraic properties of a matrix of cumulants of order 2q, C2q,x(l), whose coefficients are the circular cumulants of order 2q, Cum[xi1(t), . . . , xig(t), xiq+1(t)*, . . . , xi2q(t)*], of the observations received on each antenna, for cumulant rankings indexed by l, are utilized to define a signal subspace and a noise subspace.
Abstract:
A method for fighting interference in a communication system is disclosed where the links are of frequency-hopping type. The signal has several frequency time slots. The system has at least one main sensor and one or more auxiliary sensors, one or more guard band are inserted between the useful bands of the frequency-hopping signal. The total area of the inserted guard bands is chosen so as to satisfy a chosen value of probability of interference interception. The signals of the inserted guard bands are selected whose level is greater than a given threshold. A set of spatial-filtering weightings are determined, for each time slot of the signal, by taking account of the correlation matrix of the noise plus jammers alone on the signals selected. The baseband signals of the assemblage of extended blocks are filtered by the set of calculated weightings of the time slot so as to generate extended blocks devoid of interference.
Abstract:
Blind or partially blind process to determine characteristic space-time parameters of a propagation channel in a system comprising at least one reception sensor receiving a signal y(t). It comprises at least one step in which the specular type structure of the channel is used and a step for the joint determination of parameters such as antenna vectors (a) and/or time vectors (τ) starting from second order statistics of the received signals.Application for monitoring the spectrum of a propagation channel for positioning purposes starting from one or several HF stations or for standard communication links with equalization or positioning or spatial filtering.