On the remarkable performance of the series-resonance CMOS oscillator

Common harmonic oscillator topologies, such as class-B and class-C, are typically unable to meet ultra stringent phase noise requirements, due to the exceedingly large capacitance (and, symmetrically, low inductance) that would be required in the parallel resonator. In this paper, we show that an oscillator making use of series resonators is ideally able to overcome this limitation, with the additional, surprising benefit that the phase noise contribution from the active oscillator core can be made negligible, provided that very good MOS switches are available.