A Fast Startup Crystal Oscillator Based on Phase-Error Correction Technique
With the development of ultra-low power(ULP)Internet of Things(IoT)systems,fast startup crystal oscil-lators with energy injection techniques have gained popularity due to their significant impact on the power consumption of IoT systems.Energy injection technology can significantly reduce the startup time and startup energy of the crystal oscilla-tor but imposes strict restrictions on the accuracy of the injection source.To enlarge the injection frequency-mismatch toler-ance and achieve high-efficiency injection,this work presents a delay locked-loop assisted phase-error correction tech-nique.The injection frequency-mismatch tolerance is enlarged to 2％,and the non-injection duration of the start-up is only 4 cycles,achieving high injection efficiency.The proposed crystal oscillator is designed and fabricated in a 40 nm CMOS process.The prototype is tested with a 24 MHz crystal under 1.0 V supply.It achieves 7.2 μs startup time and consumes 5.1 nJ startup energy under 2％-injection-frequency-mismatch injection.Compared to the traditional injection with 2％in-jection frequency mismatch,this work achieves a startup time shorted by 99.66％.
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