A CMOS self-regulating VCO with low supply sensitivity

This paper presents a self-regulating voltage-controlled oscillator (VCO) with low supply sensitivity. With an adaptive delay cell, the self-regulating VCO achieves a low supply sensitivity of 0.15%-delay/1%-supply or less. This delay cell has a built-in compensation circuit that senses and corrects the delay variation caused by supply fluctuation. The proposed scheme rejects device noise as well and hence achieves a low phase noise of -101.4 dBc/Hz at 600-kHz offset when it runs at 900 MHz. The prototype phase-locked loop with the VCO fabricated in 0.35-μm CMOS process shows a cycle-to-cycle rms jitter of 2.1 ps at 450 MHz (VCO at 900 MHz) under quiet supply condition.