A history of the development of CMOS oscillators: The dark horse in frequency control

Microelectronic technologies developed over the past decade to replace quartz crystal resonators (XTALs) and oscillators (XOs) are discussed. A new figure-of-merit (FOM) is proposed to compare these emerging technologies. It is shown that CMOS oscillators (COs) have been an underestimated technology amidst these efforts as the performance of COs is comparable to existing and emerging technologies and continues to scale. Motivations and concepts behind COs are presented along with native and package-induced frequency drift mechanisms. Design and packaging approaches that minimize drift are demonstrated. A brief history of CO product embodiments is presented. State-of-art CO performance is reported where better than ±25 ppm frequency drift is achieved over 0 to 70°C and less than 950 fs_RMS phase jitter integrated from 12 kHz to 20 MHz is realized.