Phase Noise Amplitude Dependence in Self-limiting Wine-glass Disk Oscillators

Self-limiting 46.4-MHz series resonant reference oscillators employing a wine-glass mode disk micromechanical resonator to avoid hard limiting without the need for ALC have achieved measured phase noises of -113 and -134 dBc/Hz at 1kHz and far-fromcarrier offsets, respectively. When divided down to 10MHz frequency for fair comparison with other oscillators, these values correspond to -126 dBc/Hz and -147 dBc/Hz, which now satisfy specifications for low-end cellular handsets. For these oscillators, 1/f phase noise is found to be independent of vibration amplitude for amplitudes below critical Duffing, which pares down the list of possible mechanisms to those that are amplitude independent.