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Abstract

An FPGA combines antifuse and static memory cell programing technologies. Static memory cells determine the functions of the FPGA logic cells. Antifuses establish routing through the interconnect structure. Associated with each logic cell are configuration control units which store configuration information which configures the cell during normal operation. Each configuration control unit includes an SRAM memory cell. For each input terminal of a logic cell an SRAM configuration control unit selects whether an input signal is inverted or not. Other SRAM cells control whether a signal is cascaded into the logic cell from an adjacent cell, whether the cell operates as a combinational element or a latch, and whether the cell performs NOR or NAND functions. In a preferred embodiment, the configuration control units are used for three purposes: first for applying programing voltages to antifuses in the interconnect structure, second for storing configuration information which configures the cell during normal operation, and third for allowing a user to capture the status of all signals on interconnect lines and shift these out of the chip to be examined by the user.

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First Claim