An 11.1nJ-Start-up 16/20MHz Crystal Oscillator with Multi-Path Feedforward Negative Resistance Boosting and Optional Dynamic Pulse Width Injection

This paper presents a fast start-up crystal oscillator (XO) that reduces both start-up time and energy via an elegantly effective muti-path feedforward ∣ RN ∣ boosting technique. To further improve start-up speed, yet with a more energy/cost-favorable imprecise on-chip ring oscillator, an optional dynamic pulse width (DPW) injection is also proposed. The proposed fast start-up technique is implemented in 65nm process and works with 20MHz and 16MHz crystals, achieve start-up times of 30μs and 34μs while consuming 11.1nJ and 13.2nJ, respectively. Multiple chips are measured over temperature and supply voltage to verify the robustness of the employed techniques.