Patent ID: 7940103

Claim:
A duty cycle correction system, comprising: a duty cycle adjustor configured to receive an input signal, the duty cycle adjustor being responsive to a duty cycle control signal to adjust the duty cycle of the input signal to provide an output signal, the duty cycle adjustor comprising: a first delay line receiving a first signal corresponding to the input signal, the first delay line being configured to generate a first delayed signal having a delay from the first signal corresponding to the duty cycle control signal; a second delay line receiving a second signal that is a compliment of the first signal, the second delay line being configured to generate a second delayed signal having a delay from the second signal corresponding to the duty cycle control signal; a phase combiner coupled to receive the first delayed signal and the second delayed signal from the first and second delay lines, respectively, the phase combiner being configured to generate the output signal with a rising edge corresponding to specific transitions of one of the first and second delayed signals and a falling edge corresponding to specific transitions of the other of the first and second delayed signals; a variable delay line coupled to the output of the duty cycle adjustor, the variable delay line being configured to delay a signal applied to its input by a delay responsive to a delay control signal; and a phase detecting system having a first input coupled through a first signal path to the output of the duty cycle adjustor and a second input coupled to the output of the duty cycle adjustor through a second signal path wherein the second signal path includes the variable delay line, the phase detecting system adjusting the duty cycle control signal responsive to a comparison of transitions of signals applied to its inputs, the phase detecting system further adjusting the delay control signal responsive to a comparison of the transitions of signals applied to its inputs.