Self-injection-locked divide-by-3 frequency divider with improved locking range, phase noise, and input sensitivity

In this paper, we integrate a divide-by-3 injection-locked frequency divider (ILFD) in CMOS technology with a 0.18-μm BiCMOS process. We propose a self-injection technique that utilizes harmonic conversion to improve the locking range, phase-noise, and input sensitivity simultaneously. The proposed self-injection technique consists of an oddto-even harmonic converter and a feedback amplifier. This technique offers the advantage of increasing the injection efficiency at even harmonics and thus realizes the low-power implementation of an oddorder division ILFD. The measurement results using the proposed self-injection technique show that the locking range is increased by 47.8% and the phase noise is reduced by 14.7 dBc/Hz at 1-MHz offset frequency with the injection power of-12 dBm. The designed divide-by-3 ILFD occupies 0.048 mm² with a power consumption of 18.2-mW from a 1.8-V power supply.