US Patent 7746104 Dynamically controlled output multiplexer circuits in a programmable integrated circuit

A programmable integrated circuit includes a plurality of interconnected logic blocks, each including a logic circuit and an output multiplexer circuit. The output multiplexer circuit includes a first multiplexer having first and second data inputs respectively coupled to first and second outputs of the logic circuit, a select input coupled to an output of another logic block, and a first data output. A second output multiplexer may also have first and second data inputs respectively coupled to the first and second outputs of the logic circuit, a select input coupled to the output of the another logic block, and a second data output. The output multiplexer circuit is programmably coupled, in one of a plurality of operating modes, to provide an output token with the first output of each logic block only when the output multiplexer circuit of the logic block receives tokens indicating valid new data on each of the first, second, and select inputs of the circuit.