Wide-range CMOS reference clock generator with a dynamic duty cycle scaling mechanism at a 0.9-V supply voltage

This paper presents a wide-range CMOS reference clock generator with a dynamic duty cycle scaling mechanism. A new duty-cycle-to-voltage converter (DCVC) is proposed for the clock generator, which requires only the duty cycles of differential 25-MHz input signals. When these duty cycles are set into the DCVC, dual control voltages, namely V_P and V_N with positive and negative control duty cycle coefficients, respectively, are produced to manage the current sources of the differential voltage-controlled ring oscillator and supply a wide range of frequency channels. The proposed clock generator can supply a stable output clock with a wide range of frequencies from 37 kHz to 34 MHz. Notably, the wide-range CMOS reference clock generator can also be used in a universal serial bus hub or in wide band applications with low supply voltages and small areas.