A 16-MHz Crystal Oscillator With 17.5- μ s Start-Up Time Under 10-ppm- Δ F Injection Using Automatic Phase-Error Correction

Zixuan Wang, Xin Wang, Ka-Meng Lei, Wenjing Zhang, Yunjin Yin, Tailong Xu, Zhikuang Cai, Yufeng Guo, Pui-In Mak

Abstract: Fast start-up crystal oscillators (XOs) based on energy injection with an auxiliary oscillator (AO) are efficacious in improving the energy consumption of duty-cycled the Internet of Things (IoT) devices. Nonetheless, the frequency mismatch ( ${\Delta } {F}$ ) between the injection frequency and the crystal’s resonance frequency restrains the injection efficiency and start-up improvement. This work presents an automatic phase-error correction (APEC) technique for automatically correcting the phase error incurred due to ${\Delta } {F}$ up to $10{^{4}}$ ppm and safeguarding the XO start-up performance. An inflection detector (ID) based on a dynamic comparator (DCMP) traces the crystal resonant signal’s peak points and selects the appropriate signals for injection. We fabricated the proposed fast start-up XO in a 40-nm CMOS process. It achieves a start-up time of $17.5~{\mu }$ s with a 16-MHz crystal and a 1.0-V ${V} {_{\text {DD}}}$ . Furthermore, the start-up time only varies by ±1.42% over a ${\Delta } {F}$ of ${\pm } 10{^{4}}$ ppm, and ±4.5% amid temperature variations (−40°C to $85~{^{\circ }}$ C), evincing the robustness of the proposed technique. The power consumption and phase noise in the steady state are $84~{\mu }$ W and −139 dBc/Hz at 1-kHz offset, respectively.