This letter presents a low-power single-ended active inductor with its Q-factor enhanced by feedback. Without sacrificing the self-resonance frequency and increasing the DC power consumption of the main circuit, the feedback transistor introduces a negative resistance; therefore, high Q-factors can be achieved in a wide operating frequency range. The proposed inductor was designed in a 0.13 μm CMOS process and simulated using Cadence Spectre. The active area is ~4 μm × 5 μm. With ~0.1 mW power consumption, the designed active inductor shows a 17 GHz maximum self-resonance frequency and a 1–8 GHz peak-Q operating frequency range. Using this active inductor, a 3-bit digitally-controlled phase shifter was designed. The phase shifter can provide a phase shift range larger than 180° from 1.5 to 4 GHz and a return loss better than 10 dB.