Patent ID: 7679408

Claim:
A circuit for managing clock signal switching with logic devices, comprising: an asynchronous clock group comprising one or more glitchless control blocks for outputting asynchronous clock signals; one or more synchronous clock groups comprising a plurality of glitchless control blocks for outputting synchronous clock signals; and a multiplexer for receiving delayed input clock signals from the glitchless control blocks for outputting asynchronous clock signals and delayed input clock signals from the glitchless control blocks for outputting synchronous clock signals; wherein a switching latency from a first input clock signal which belongs to a synchronous clock group in the one or more synchronous clock groups to a second input clock signal which belongs to the synchronous clock group is one clock cycle or less of the second input clock signal; wherein the switching latency is a period in which no clock pulse appears at a final output clock signal of the circuit; and wherein select inhibit terminals in each glitchless control block for the synchronous clock group are connected directly to a combinational gate in each glitchless control block, such that an output signal from the combinational gate passes through only one D flip-flop to generate an enable signal one cycle earlier than other switching cases in which the output signal from the combinational gate passes through at least two stages of D flip-flops.