Thomson-csf

Thales

Pascal Gabet

Jean-Luc De Gouy

Gilles Neveu

Philippe Benabes

A divider to divide a frequency Fcomprises at least the following elements: three flip-flop circuits, each of the flip-flop circuits receiving the frequency to be divided, every feedback loop between an output of a flip-flop circuit and its input or the input of the other flip-flop circuits comprising a single multiplexer, wherein one of the flip-flop circuits commands the loading of all the flip-flop circuits during one period of the frequency A multiplexer has two inputs, one selection bit and one output and is integrated into a flip-flop circuit.

Frequency divider

A method and device of frequency division with a division ratio: comprising: an input divider with a division ratio NPs receiving the frequency Fe at input and delivering a signal to an insertion/substitution divider, the insertion/substitution divider having an input of variation of the division ratio, delivering a command frame to the input divider and generating an end-of-count signal, the insertion/substitution divider being adapted to the insertion of one or more input divider cycles and/or the substitution of an input divider cycle in the command frame.

Frequency division method and device

In a frequency divider enabling the division by N of a frequency Fe and comprising at least one prescaler followed by a division chain, the prescaler has at least one input for the frequency signal Fe to be divided, one input for a command NA of the basic division rank of the prescaler and one input for a command &#x394;NA coming from the division chain and enabling NA to be made to vary by one unit; the division chain comprises at least one division stage (K) comprising at least one divider by 2, giving a divided frequency F(K), a switch controlled by the divider by 2, the switch having one input for a piece of programming data R(K), one input for the carry signal RX(K+1) of the next stage and one output for the carry signal RX(K) for the previous stage. Application to the field of phase-locked loop frequency synthesis.

Frequency divider with funnel structure

A direct digital frequency-synthesis device includes a modulo-M coherent accumulator that generates a first phase law from a frequency-control word. A table, addressed by a second phase law derived from the first phase law, generates a digital sinusoidal signal. A digital/analog converter converts the digital sinusoidal signal into an analog sinusoidal signal. A filter filters the analog sinusoidal signal. And, a divider divides the filtered signal. The divider has a lower order than M and has a synchronization input driven by a synchronization pulse for re-synchronizing the signal after division, the synchronization pulse being derived from the phase law. Such a device may find particular application to digital synthesizers for radar.

Digital synthesizer with coherent division

Method and device for the generation of a random signal with controlled histogram and spectrum

A sigma-delta modulator having a propagation delay &Dgr;t between an input of an analog-to-digital converter and an output of the digital-to-analog converter. A subtractor is located in a direct chain between an amplification unit and the analog-to-direct converter. The output of the amplification unit is connected to a first direct input of the subtractor. An output of the subtractor is connected to the input of the analog-to-digital convertor. The modulator also includes a compensation filter located between the output of the subtractor and a second inverter input of the subtractor. When considering an impulse response of the modulator, at the output of the subtractor, to an impulse sent at the output of the subtractor, including a first part covering a first time interval 0; T with T&gE;&Dgr;t, and a second part covering a second time interval T; &prop;, the compensation filter is designed to contribute to the first part and the amplification unit is designed to contribute only to the second part. Such a sigma-delta modulator may be used in a radar processing chain.

Delay compensation for analog-to-digital converter in sigma-delta modulators

Method and device for generating a random signal and digital-to-analog converting systems using same

A digital frequency synthesizer comprises means for the generation of the samples of a digital signal to be converted into an analog signal encoded on N bits as a function of a frequency control word, means for the generation of a noise signal encoded on N bits, and a digital-analog converter, the useful signal and the noise signal being truncated to M bits before being added up by an adder. The result of the addition is converted into analog signal form by the digital-analog converter. The generated noise has at least a noise density substantially equal to a law of equiprobability, this density being zero outside a given space. Application especially to direct digital synthesis, for example in the field of radar techniques or that of instrumentation.

Digital synthesizer of signals

Present-day single or multiple fractional phase-locked loop frequency synthesizers are not phase coherent for they use a digital accumulator modulo a number P with a variable increment K, whose state is a function of the history of the change in values that have been imposed on the increment. This lack of phase coherence rules out the use of these synthesizers in certain fields such as that of Doppler radars. A novel type of single or multiple fractional phase-locked loop frequency synthesizer that is coherent in phase is proposed herein. This type of synthesizer comprises one or more counters with an increment of one, having their rate set by the reference oscillator of the synthesizer and being used in phase memories to enable changes in the increment or increments following a change in the fractional division ratio at instants that are synchronous with the reference oscillator.

Fractional phase-locked loop coherent frequency synthesizer

A device for the generation of analog signals by means of analog-digital converters comprises a block for the generation of words encoded on N bits and an analog-digital converter whose input is encoded on M bits, M being smaller than N. The device furthermore comprises a sigma-delta modulator, at the output of the first block, the bus being separated into M most significant bits reserved for the input of the analog-digital converter and N-M least significant bits that enter the sigma-delta modulator, the output of this modulator being an M-bit bus that is added to the M output bits of the word generation block by digital addition means, M being smaller than N.

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Cholet, France

Pascal Gabet