Abstract: A multi-stage frequency divider includes a cascaded arrangement of first and second integer dividers configured to collectively divide a frequency of a periodic reference signal by an integer amount equal to a product of (2N+1) and (2M+1), where N and M are unequal positive integers greater than two. A duty cycle enhancement circuit is provided, which is synchronized to the periodic reference signal and configured to generate a periodic signal having 2MN+N+M cycles of high followed by 2MN+N+M+1 cycles of low or vice versa, where a duration of each cycle is equivalent to a period of the periodic reference signal. A duty cycle correction circuit is provided as a final stage and is configured to generate a periodic output signal having a uniform duty cycle from the periodic signal generated by the duty cycle enhancement circuit.

Abstract: A programmable delay generator includes a calibration circuit and a delay line responsive to a calibration control signal generated by the calibration circuit. The calibration circuit includes a digitally-controlled oscillator (DCO) having a first plurality of delay stages therein. A frequency of the DCO is set by the calibration control signal. The delay line includes a second plurality of delay stages that are replicas of the first plurality of delay stages. The calibration circuit may include a current steering digital-to-analog converter (CSDAC), which is responsive to a digital calibration code, and a current-to-voltage converter, which is responsive to at least one current signal generated by the CSDAC. The DCO and other portions of the calibration circuit are disabled into a low power state upon completion of a calibration operation, which may commence upon start-up.

Abstract: A Phase-Locked Loop (PLL) system (30) and a method for modifying the output transition time of the PLL system (30). The PLL system has an input stage (36) connected to a PLL (37). The input stage (36) includes a phase detector stage (47), a phase difference threshold stage (48), and a phase difference modification stage (49). The input stage (36) receives a reference input signal and a feedback input signal and determines the phase difference between these two input signals. If the phase difference is greater than a predetermined value, then the input stage (36) decreases the phase difference between the reference input signal and the feedback input signal. If the phase difference is less than the predetermined value, then the phase difference between the reference input signal and the feedback input signal is not modified.