Logic cell for programmable logic device

Abstract

A logic cell in a programmable logic device receives an external signal from a routing network that serves as a select signal that selects a combinatorial logic signal via a first multiplexor as well as a data input to a second multiplexor. The second multiplexor selects between the combinatorial logic signal and the external signal and provides an output signal to a register. Accordingly, the logic cell has the flexibility to support a combinatorial and/or sequential function using minimal routing resources. A third multiplexor may select the output from the register or another signal as the output signal from the logic cell. A clock signal to the register may be gated off when the register output is not selected as the output signal, thereby reducing dynamic power consumption. The programmable logic device may include a number of super logic cells, each of which includes a plurality of logic cells.