On the injection methods in a top-series-injection-locked frequency divider

This paper proposes a top-series-injection-locked frequency divider (ILFD) with a tunable active inductor with variable division ratio and studies the effect of injection methods on the property of ILFD. With only the differential injection method the ILFD has the modulus of 1, 2, 3, 4, and 5. The ILFD was fabricated in the 0.18 μm 1P6M CMOS technology, and at the supply voltage of 1.5 V, the free-running divider is tunable from 0.13 GHz to 2.93 GHz. The ILFD has wide-operation locking ranges in both divide-by-2 and divide-by-3 mode.