A Fast-Startup 80MHz Crystal Oscillator with 96x/368x Startup-Time Reductions for 3.0V/1.2V Swings Based on Un-interrupted Phase-Aligned Injection

This paper presents an 80MHz crystal oscillator with fast-startup capability based on phase-aligned clock injection. The instantaneous phase misalignment due to frequency error is detected in real time without interrupting the injection process. The injection clock's frequency is corrected accordingly and gradually approaches the crystal oscillator's intrinsic oscillation frequency. Very effective start-up acceleration is demonstrated as benchmarked against ideal injections with zero frequency error. A prototype circuit in 55nm CMOS process achieves 96x and 368x startup time reductions for 3.0V and 1.2V target swings, respectively.