Some embodiments of the invention provide a configurable integrated circuit (“IC”). The configurable IC includes a set of multiplexers that each has a set of input terminals, a set of output terminals, and a set of select terminals. The set of multiplexers includes a group of multiplexers, where at least one input terminal of each multiplexer in the group is a permanently inverting input terminal. During at least a set of cycles during the operation of the configurable IC, several multiplexers in the group of multiplexers are used to implement a particular function.