Fast Startup Real-Time Clock Design

This paper presents a real-time clock circuit based on a fast-starting crystal oscillator and a low-power crossover circuit. By connecting the matching capacitor of the oscillator to the supply voltage instead of grounding the matching capacitor of the traditional oscillator, the noise in the supply voltage is again introduced into the oscillator circuit, and the noise current is increased to improve the starting speed and stabilization speed of the crystal oscillator. The crossover circuit uses two types of crossover circuits to process the signal at high and low frequencies separately to ensure signal accuracy and reduce power consumption, compared to the traditional single crossover circuit for crossover. Experimental simulation results using the SMIC 130nm process show that the circuit can achieve startup within 153mS and stable oscillation within 430mS at room temperature and 3V supply voltage with an operating current of 0.74uA.