A negative-feedback scheme is applied to the gain stage of RC and LC ring oscillators to extend the frequency tuning range and to enhance the maximum oscillation frequency, respectively. This can be achieved without penalties in power consumption, supply voltage and silicon area. To verify the operation of the proposed topology, the theory of a three-stage shunt-feedback ring oscillator has been developed and compared with simulation results. Differential versions of 1.2-V shuntfeedback RC and LC ring oscillators operating, respectively, at 5 GHz and 11.6 GHz are demonstrated by simulations using a 0.18-μm CMOS technology.