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A CMOS injection-locked frequency divider (ILFD) with high division ratios and high frequency operation is presented. It consists of a ring oscillator and injection capacitors. An input signal is directly injected through the capacitors into the feedback nodes of the ring oscillator. The proposed ILFD is fabricated in a 0.18 mum CMOS process and has a chip core size of 68 mum times 70 mum. It shows multiple division ratios of 3, 6, and 9. The operation frequency is from 2.2 to 30.95 GHz. At the maximum operation frequency, the ILFD has a locking range of 260 MHz with an input power of less than 0.25 dBm, a division ratio of 9, and a power consumption of 12.5 mW. The locking range increases up to 3.2 GHz as the division ratio and the operation frequency decrease.