Abstract: A crystal oscillator achieves fast start-up by injecting an in-band periodic signal into the crystal oscillator driver circuit. The in-band periodic signal has a frequency that is within a bandwidth of the crystal oscillator. Injection of the in-band periodic signal begins in response to a power-up condition and stops after a predetermined time period corresponding to the amount of time it takes to ensure the crystal driver is achieving full swing.

Abstract: A phase locked loop (PLL) includes a first loop, a second loop, and a lock detector. The first loop locks a feedback signal having a frequency equal to a fraction of a frequency of an output signal to a reference signal in phase. The first loop has a first bandwidth. The second loop locks the feedback signal to the reference signal in frequency and has a second bandwidth. The first bandwidth is higher than the second bandwidth. The lock detector is coupled to the second loop and increases the second bandwidth in response to detecting that the feedback signal is not locked to the reference signal.

Abstract: A phase locked loop (PLL) includes a first loop, a second loop, and a lock detector. The first loop locks a feedback signal having a frequency equal to a fraction of a frequency of an output signal to a reference signal in phase. The first loop has a first bandwidth. The second loop locks the feedback signal to the reference signal in frequency and has a second bandwidth. The first bandwidth is higher than the second bandwidth. The lock detector is coupled to the second loop and increases the second bandwidth in response to detecting that the feedback signal is not locked to the reference signal.

Abstract: An integrated circuit includes a feedback controlled clock generating circuit, such as a DLL, PLL or other suitable circuit, that is operative to provide a feedback reference frequency signal based on a generated output clock signal. The integrated circuit also includes a programmable fine lock/unlock detection circuit that includes programmable static phase error sensitivity logic that senses phase error. The programmable static phase error sensitivity logic sets a phase lock sensitivity window used to determine a fine lock/unlock condition of the generated output clock signal. The programmable fine lock/unlock detection logic is also operative to generate a fine phase lock/unlock signal based on the set phase lock sensitivity window. The integrated circuit may also include a coarse lock detection circuit that generates a coarse lock signal based on a frequency unlock condition.