Ultra low phase noise 2.1 GHz Colpitts oscillators using BAW resonator

This paper describes the design and the realization of a 2.1 GHz ultra low phase noise oscillator using BAW resonator and fabricated in BiCMOS technology. The oscillator is intended for a chip scale atomic clock (CSAC). Based on the Colpitts topology, two circuits have been designed and realized. These circuits can achieve a phase noise better than -83 dBc/Hz at 2 kHz offset, consume less than 10 mA and the area of the die is less than 2 mm². To the author´s knowledge, these BAW oscillators present the lowest phase noise published in the literature.