Design of Ring-Oscillator-Based Injection-Locked Frequency Dividers With Single-Phase Inputs

Ring-oscillator-based injection-locked frequency divider has merits of compact and low power. The multi-phase injection can improve its locking range, but it needs specific multi-phase inputs, which limits the application of this technique. We present a symmetrical injection circuit to generate the multi-phase injection with only single-phase input. Two injection-locked frequency dividers, with divide-by-3 and divide-by-5 operations respectively, were fabricated in 0.18 μ m CMOS technology to verify the proposed design. The locking range of divide-by-3 and divide-by-5 dividers are 1.6 GHz and 0.9 GHz, with 0.24 and 0.7 mW power consumption in 1 V supply voltage, respectively.