Unisys Corporation

Fernando W Arraut

Laszlo V Gal

Larry L Byers

Dale K Seppa

Christopher H Khosravi

Robert C Shen

An apparatus for a transparent master/slave flip-flop logic circuit including a single line connected to the transparency input of the logic macro so that when the line is active input data will pass through the flip-flop, unless the scan signal is also active, in which case the flip-flop will return to a clocked (latching) status.

Transparent flip-flop

A logic cell, for use in a semicustom chip, is comprised of a plurality of transistors that are integrated into a semiconductor substrate and are interconnected within the cell to perform a logic function. This cell has sidewalls which define the space in the chip which contains all the transistors and their interconnections within the cell; at least one of the sidewalls is shaped to include a step which gives the cell a narrow top and a wide bottom; and one or more of the cell's transistors lies below the step in the wide bottom of the cell. Many of these cells are arranged in spaced apart rows on the semicustom chip in which the narrow tops of the cell line up. Conductors which interconnect the cells are disposed in the space between the narrow tops of the cells and over the transistors in the wide bottoms of the cells. Using this architecture, the density with which a logic cell is integrated to a semicustom chip is improved more than 100%.

Semicustom chip whose logic cells have narrow tops and wide bottoms

A synchronizer is comprised of a voltage amplifier having an input terminal for receiving a voltage sample and an output terminal for generating an output voltage that is inversely proportional to the voltage of the input terminal. Also, a first feedback circuit couples the output terminal to a control transistor internal to the amplifier, and a second feedback circuit couples the output terminal to the input terminal. The first feedback circuit together with the control transistor has a fast response time, in comparison to the second feedback circuit; and it operates to quickly increase the output voltage when the voltage sample on the input terminal is below a predetermined level, and vice versa, without altering the voltage sample on the input terminal. And, the second feedback circuit operates to slowly modify the voltage sample on the input terminal in inverse proportion to the output terminal voltage.

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San Diego, CA, United States of America

Fernando W Arraut