International Business Machines Corporation

Martine Bonneau

Pierre B Mollier

Gerard Boudon

Robert M Hornung

Ieng Ong

Eric Gouze

Jean-Marc Piccino

Jean-Claude Le Garrec

Frank Wallart

A CMOS FET master slice integrated circuit (20) of the gate-array type implemented in a semiconductor logic chip, comprises a plurality of core cells (CELL1, CELL2, . . . ) arranged adjacent one another on a repetitive basis in a row direction to form horizontal stripe shaped functional gate region (21) of a determined height (H). Each core cell (e.g., CELL1) is comprised of four different sized devices: one small and one large NFET (N1.1, N2.1), thus one small and one larger PFET (P1.1, P2.1), that are disposed in a column direction. The NFETs have separate gate electrodes (GN1.1, GN2.1) to define individual devices, while the PFETs have preferably a common gate electrode (GP1) to define a single device. The relative size of NFETs and PFETs have been optimized to provide the required functionality to the latches and to ensure the balanced rise and fall delays in a maximum of basic logic circuits of the chip. As a result, the use of such core cells, allows that complex logic functions, such as latches, can be implemented in gate arrays that have a density and performance comparable with standard cell circuits. In addition, the use of these core cells also permits optimization of other basic logic circuits (INV, NOR, . . . ) that are used in critical logic paths and clock distribution trees, where balanced delays are highly desirable.

Gate array cell having FETs of different and optimized sizes

The invention provides novel implementations of a latch cell in CMOS gate array technology to produce latch dissymmetry and permit a single ended data input. The dissymmetry is produced by increasing the output impedance of the second stage of the latch cell, which can be done, either in a DC or in an AC mode, or even in a mixed version of both modes.

Latch cell family in CMOS technology gate array

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Itteville, France

Martine Bonneau