US Patent 7197104 Minimum gate delay edge counter

An edge counter counting both rising and falling edges of an input signal is implemented with combinational logic, without using flip-flops. The combinational logic is designed using intermediate signals and state transitions producing an output signal having a cycle corresponding to a predetermined odd or even number of input signal edges, with the logic optimized and protected against entry into “stuck” states. A low power, low gate count edge counter is thus implemented with an output signal duty cycle at least as balanced as the input counter duty cycle.