Investigation of on-chip phase-noise reduction using self-injection technique on fully integrated frequency dividers

Significant phase-noise improvement is demonstrated using a self-injection technique on a fully integrated 0.18-μm CMOS divide-by-3 (1/3) injection-locked frequency divider (ILFD). The self-injection is realized with an odd-to-even harmonic converter followed by a feedback-amplifier. The self-injection 1/3 ILFD shows superior injection efficiency due to the increased self-injection signal which results in substantial phase noise reduction. The phase noise is improved by 14.77 dB at 1-MHz offset when the self-injection loop is enabled. The core of the 1/3 ILFD occupies 0.048-mm² area and dissipates 18.2-mW from a 1.8-V power supply. The phase-noise reduction technique can be implemented for other kinds of ILFDs.