A 16-MHz Crystal Oscillator With 17.5- μ s Start-Up Time Under 104-ppm- Δ F Injection Using Automatic Phase-Error Correction

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.