An NMOS inductive loading technique for extended operating frequency CMOS ring oscillators

The circuit architecture of the active inductive load based upon an nMOS transistor for frequency enhancement in CMOS ring oscillators is described. Emphasis is given to the performance analysis and design guidelines of the inductive loading technique as well as its theoretical comparison with the ordinary resistive loading ring oscillator. Implemented using a 0.35 /spl mu/m, 3.3 V CMOS process, the simulated 3-stage nMOS inductive ring oscillator meet the specified target at 2.4 GHz even at slow process extreme and 125/spl deg/C temperature while consuming less than 47.5 mW of power.