A mutual-negative-resistance quadrature CMOS LC oscillator

An enhanced quadrature LC oscillator based upon the cross coupling between two magnetic-coupled or mutual negative-resistance oscillators is presented. The use of the mutual-R topology results in the entire elimination of the cross-coupling devices normally required when the traditional negative-G_m oscillator topology is used, thereby yielding significant benefits to power consumption and phase noise performance. Practical simulated results of 3 GHz single and quadrature-phase mutual-R oscillators in a 0.25 μm CMOS technology demonstrate the capability of the topology over the conventional negative-G_m approach.