A 3 μW, 400 MHz divide-by-5 injection-locked frequency divider with 56% lock range in 90nm CMOS

An ultra-low power injection locked frequency divider (ILFD) is presented and demonstrated. Based on a 5-stage single ended ring oscillator, the ILFD achieves a lock range of 56% at a division ratio of 5 in the medical implant communications service (MICS) and the 433 MHz ISM frequency bands. The ILFD is implemented in a 90 nm CMOS process. It consumes 3 muW of power from a 1.0 V supply and 100 mum
²
of area. The circuit achieves a frequency divider figure-of-merit of 134 GHz/mW.