A Fast Startup Crystal Oscillator Using Impedance Guided Chirp Injection in 22 nm FinFET CMOS

Abstract

An Impedance Guided Chirp Injection (IGCI) oscillator-based fast startup technique is proposed in this work demonstrating startup time between 5 and 100 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> across a wide range of oscillator frequencies. The IGCI technique can efficiently detect the resonance frequency of the crystal and provide energy injection for fast crystal startup. The simplicity of the implementation of the IGCI circuitry enables easy porting across technology nodes and interfacing with different oscillator topologies. Compared to previous negative resistance boosting or open-loop injection techniques, the proposed IGCI achieves both faster startup and lower injection power which reduces the overall startup energy. A test chip is fabricated in Intel 22FFL technology and the measurements are performed using 38.4 MHz crystal achieving ~2.6 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times $ </tex-math></inline-formula> faster startup than normal startup (with same biasing, load cap) without any injection. Extensive measurements are performed across different temperatures and multiple startup occurrences.