Injection-Locked Frequency Divider Topology and Design Techniques for Wide Locking-Range and High-Order Division

An injection-locked frequency divider topology for wide locking-range and high-order division is presented. Based on the theoretical analysis of the locking-range and injection locking characteristic, we propose locking-range enhancement techniques and high-order dividing topology. Fabricated in a 0.18-mu m BiCMOS process, three test circuits are designed with only a standard CMOS, aiming at input frequency ranges of 7.8, 11.1, and 11.7 GHz. The 7.8-GHz divide-by-2 ILFD consumes 2.9 mW with a locking range of 692 MHz operated from a 1.5 V supply. The optimized dual injection method improves the locking range by a factor of 10. The 11.1-GHz divide-by-3 ILFD employs an even-harmonic phase tuning technique and the proposed technique improves the locking range by 25%. The core of the 11.1-GHz ILFD consumes 6.15 mW from a 1.8 V supply. For the 11.7-GHz divide-by-3 ILFD, a self-injection technique is proposed that utilizes harmonic conversion and self-injection to improve phase-noise, locking-range, and input sensitivity simultaneously. By employing harmonic tuning and self-injection, odd-order division is enabled with 47.8% enhancement in the locking-range and 15.7-dBc/Hz reduction in phase noise.