Nec Corporation

Minoru Kayano

Yasushi Aoki

Mitsuo Baba

Atsushi Katayama

Yuuji Takahashi

Kousuke Uno

A bit synchronization circuit extracts the central phase of an eye opening irrespective of a jitter distribution of input data to maintain an optimum timing adjustment margin. The bit synchronization circuit has a data edge detector for comparing the phases of an edge of the input data and m-phase clock signals divided from a reference clock. Data edge phase information from the data edge detector is accumulated by a phase accumulation register, which stores the jitter distribution of the input data as accumulated phase information. Based on the accumulated phase information, an eye center phase calculator decodes the negative and positive ends of a jitter range as negative jitter range information and positive jitter range information, and calculates a phase control direction in relation to an extracted phase value which represents a presently selected clock phase. A correction circuit extracts the positional relationship between a present eye opening width and the extracted phase value, and clears the accumulated phase information to increase the eye opening width.

Bit synchronization circuit

For functional blocks of an IC, each functional block comprising a plurality of macroblocks, each macroblock comprising a plurality of basic cells, a mask pattern is patterned in accordance with a layout design by using its connection data of the macroblocks in each functional block and its placement data of the basic cells in each functional block. Use of the placement data in addition to the connection data makes it possible to regularly and systematically arrange the basic cells in each functional block to achieve shortest possible connections in each fundamental block and a narrowest possible area of each functional block. In order to put a CPU in operation of patterning the mask pattern, an operating system comprises for read by the CPU first and second memories loaded with the connection and the placement data, respectively.

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Tokyo, Japan

Minoru Kayano