A 1 ppb MEMS Oscillator Achieving -90 dBc/Hz at 10 Hz Offset Enabled by 5 M $\Omega$ TIA and 360° Phase Shifter

This paper presents a fully integrated MEMS oscillator incorporating a low-noise high gain TIA, tunable phase shifter, and drive control circuit. It is fabricated in 65 nm CMOS and features a 115–134 $\text{dB}\Omega, 81\text{fA}/\sqrt{\text{Hz}}$ TIA, a 360° phase shifter, and a 10mV - 200 mV drive control circuit. Leveraging a high Q electrostatic MEMS resonator, the oscillator achieves -90 dBc/Hz phase noise at a 10Hz offset.