Abstract: A linear PLL includes a VCO with first and second tuning elements. The first tuning element is adjusted in proportion to the phase error between an input signal and a VCO signal and the second tuning element is adjusted by an integral function of the phase error. By configuring the VCO with separate tuning elements that are separately adjusted in proportion to the phase error and by an integral function of the phase error, the 3dB bandwidth frequency of the linear PLL depends primarily on the phase detector gain and the VCO gain that is contributed from the proportional adjustment. A linear PLL with separate proportional and integral tuning elements can be designed to exhibit a relatively constant gain over a relatively large frequency range.

Abstract: The frequency changes in a bang-bang PLL that are generated using a digital phase detector's up/down signal are initially set to produce a faster pull-in rate and then reduced to produce a slower pull-in rate. The faster pull-in involves relatively large frequency changes and the slower pull-in rate involves smaller frequency changes. The changes in frequency of a bang-bang PLL can be implemented using a step size controller that includes timing control logic and step size logic. The function of the timing control logic is to control the timing of step size changes. The function of the step size logic is to set the step size of the frequency changes that are made by the VCO in response to the pd_up/down signal that is delivered directly to the VCO from the digital phase detector.

Abstract: An offset related to a feedback system for a VCO is quantified and then a parameter of the feedback system is adjusted in response to the quantified offset to correct for the offset. Correcting for offset in a feedback system can improve the performance of a PLL by reducing phase drift between the input signal and the VCO signal. The reduced phase drift can have benefits such as, for example, reduced bit errors and/or improved phase tracking accuracy.

Abstract: A technique for establishing a tuning signal window for a multi-band VCO involves setting the tuning signal window to an initial size, preferably a relatively small size, and determining whether the VCO is churning. When the VCO is determined to be churning, the tuning signal window is expanded until the VCO stops churning. In an embodiment, the tuning signal window is expanded incrementally until the tuning signal window is large enough to include a solution, where a solution is defined as an operating point along a frequency band that satisfies both the setpoint frequency and tuning window signal requirements. The tuning signal window can be set at an offset relative to the tuning signal zero to compensate for shifts in the frequency bands that may result from changes in operating conditions.

Abstract: The frequency changes in a bang-bang PLL that are generated using a digital phase detector's up/down signal are initially set to produce a faster pull-in rate and then reduced to produce a slower pull-in rate. The faster pull-in involves relatively large frequency changes and the slower pull-in rate involves smaller frequency changes. The changes in frequency of a bang-bang PLL can be implemented using a step size controller that includes timing control logic and step size logic. The function of the timing control logic is to control the timing of step size changes. The function of the step size logic is to set the step size of the frequency changes that are made by the VCO in response to the pd_up/down signal that is delivered directly to the VCO from the digital phase detector.

Abstract: A technique for correcting for DC offset in a phase locked loop involves generating digital phase information in response to an input signal and then generating an offset correction signal in response to the digital phase information. The digital phase information may include transition samples that are integrated to generate the offset correction signal. Integrating the transition samples helps to compensate for the effects of phase noise, especially phase noise that is contributed by the input signal and/or the recovered clock signal.

Abstract: Centering a multi-band VCO involves comparing a VCO tuning signal to a pre-established tuning signal window to determine whether to change the frequency band of the multi-band VCO. The frequency band of the multi-band VCO can be changed only when the tuning signal is outside the tuning signal window. Further, the frequency band can be changed as long as the VCO is being controlled by a frequency detector. Once the multi-band VCO achieves lock, the multi-band VCO is changed by at least one more frequency band as long as the VCO tuning signal is still outside the tuning signal window.