Capacitive cross-coupled injection-locked frequency dividers(ILFDs)have the merits of low power and wide locking range. This book introduces the design of wide locking range ILFDs based on capacitive cross-coupled oscillators and using multi-resonance RLC resonator. The merits are shown experimentally and by simulation. Many designed divide-by-2 and divide-by-3 ILFD examples using RLC capacitive cross-coupled oscillators are used to verify the usefulness of the design method. The design method is also a sensitive technique to find the distributed effect of on-chip inductors.