Progressive Mixing Technique to Widen the Locking Range of High Division-Ratio Injection-Locked Frequency Dividers

This paper proposes progressive mixing as a technique to widen the locking range of injection locked frequency dividers (ILFDs) with higher division ratios. The ILFD locking range for a certain division ratio depends on the harmonics that are used to generate the injection signal. Compared to the conventional ILFD, the proposed technique uses much stronger harmonics in the mixing process to generate the injection signal more efficiently for higher division ratios. This is achieved through the reuse of higher harmonics of the ILFD fundamental oscillation frequency to perform progressive or multisteps divide-by-2 mixing of the injection signal. This results in that the injection signal is mixed with much stronger harmonics compared to the conventional single-step mixing and a stronger injection is produced. Since each divide-by-2 step uses higher harmonics of the fundamental, there is no increase in power consumption while the locking range is significantly enhanced. Two progressive mixing ILFDs are designed using a 65-nm CMOS to divide-by-4 and divide-by-8. The former has an operation range from 7.3 to 21.3 GHz while maintaining a locking range greater than 31% and consuming 3.9 mW from a 1.2-V supply. The latter has an operation range from 12.6 to 24.7 GHz while maintaining a locking range greater than 15% and consuming 7.1 mW from a 1.2-V supply.