Sgs-thomson Microelectronics S.a.

Xavier Cauchy

Michel Imbert

Serge Volmier

The present invention relates to a method for regulating, in the read mode, memory areas of a circuit for decompressing a video data flow compressed according to an MPEG standard, with respect to the writing rate of the compressed data flow into the memory areas, the decompression circuit issuing a flow of image data at the rate of signals for horizontally and vertically synchronizing the images issued by a circuit for coding according to a color television standard, this method including generating a clock signal having a fixed frequency for reading from the memory areas and for generating the horizontal and vertical synchronization signals, and shifting the occurrence of an edge triggering the vertical synchronization signal based on a signal indicative of the state of a buffer memory associated with the memory areas.

Digital television signal flow regulation

A frequency-doubling block includes an input terminal for the incident signal, a first variable delay cell linked to the input, and an EXCLUSIVE OR gate, one input of which is linked to the output of the first delay cell, the other input of which is linked to the input terminal, and the output of which is able to deliver an output clock signal at twice the frequency of the incident signal. A comparison circuit compares the duty ratio of the output signal with a predetermined reference value and a modulation circuit modulates the value of the first delay as a function of the result of the comparison.

Process for multiplying the frequency of a clock signal with control of

The present invention provides a circuit capable of operating according to a normal operating mode or to a structural operating mode. The test mode is stored in an internal flip-flop via an interface of the circuit. In test mode, the flip-flop is insulated from the interface by multiplexing means. To exit the test mode, an input temporarily dedicated to this function is used, this input being then insulated by multiplexing means from the rest of the circuit.

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Meylan, France

Xavier Cauchy