Ultra-Low Phase Noise NMOS and PMOS Colpitts Oscillators Using BAW Resonator Comparison

This paper introduces a complete comparison between NMOS and PMOS differential Colpitts oscillators in a 28 nm CMOS technology and using a BAW resonator. A gm-boosting technique is implemented to enhance negative resistance and alleviate start-up constraints. $g_{m}/I_{D}$ ratio is the main used design methodology, and a direct relation with noise is demonstrated. Both oscillators present a frequency around 4.2 GHz with an ultra-low phase noise performance of -149 and - 52 dBc/Hz at 1 MHz offset for the NMOS and PMOS topologies, respectively.