In this work the phase noise performance of relaxation oscillators has been analyzed resulting in simple though precise phase noise expressions. These expressions have lead to a new relaxation oscillator topology, which exploits a noise filtering technique implemented with a switched-capacitor circuit to minimize phase noise. Measurements on a 65nm CMOS design show a sawtooth waveform, a frequency tuning range between 1 and 12MHz and a rather constant frequency tuning gain. At 12MHz oscillation frequency it consumes 90μW while the phase noise is -109dBc/Hz at 100KHz offset frequency. By minimizing and balancing noise contributions of charge and discharge mechanisms, a nearly minimal FoM of -161dBc/Hz has been achieved, which is a 6dB improvement over state-of-the-art.
|Title of host publication||Proceedings of the 19th Annual Workshop on Circuits|
|Place of Publication||Veldhoven|
|Number of pages||4|
|Publication status||Published - 29 Nov 2008|
|Event||19th Annual Workshop on Circuits, Systems and Signal Processing, ProRISC 2008 - Veldhoven, Netherlands|
Duration: 27 Nov 2008 → 28 Nov 2008
Conference number: 19
|Publisher||Technology Foundation STW|
|Conference||19th Annual Workshop on Circuits, Systems and Signal Processing, ProRISC 2008|
|Period||27/11/08 → 28/11/08|
Geraedts, P. F. J., van Tuijl, A. J. M., Klumperink, E. A. M., Wienk, G. J. M., & Nauta, B. (2008). A 12MHz Switched-Capacitor Relaxation Oscillator with a Nearly Minimal FoM of -161dBc/Hz. In Proceedings of the 19th Annual Workshop on Circuits (pp. 175-178). Veldhoven: STW.