A 44-μW 4.3-GHz injection-locked frequency divider with 2.3-GHz locking range

A microwatt frequency divider for the 2.5-GHz ISM band is proposed. This divider directly modulates the output in a ring oscillator by means of a switch and realizes low power consumption with low supply voltage and a wide locking range. It is fabricated using a five-layer-metal and 0.2-μm-gate length CMOS process. The core size is 10.8×10.5 μm², which is much smaller than that of a typical inductor-enhanced frequency divider. This divider operates with a supply voltage in the range from 1.8 to 0.7V, and attains minimum power consumption of 44 μW, in which case the supply voltage is 0.7 V, the maximum operating frequency is 4.3 GHz, and the locking range is 2.3 GHz. A derivation of the frequency locking range of the divider is provided in the Appendix.