Multi-physics modeling of electro-mechanical oscillators: Comparative analysis of Colpitts and Cross-Coupled architectures

This paper discusses necessity of multi-physics analysis methodology for electro-mechanical oscillators. Electro-mechanical coupling module is introduced to account for power-energy conversion between electro-mechanical resonators and oscillator active-cores. The proposed methodology is successfully applied to the design of low power and low noise integrated crystal oscillators using NXP-Semiconductors advanced BiCMOS QUBIC technology solutions. A phase noise better than -154dBc/Hz at 10KHz with noise supply rejection better than -65dB is experimentally demonstrated. Comparative analysis of Colpitts and Cross-Coupled oscillator architectures is proposed. Impact of CML and MOS Amplitude-Level-Control (ALC) regulation schemes on phase-noise performances are investigated. Correlations of experimental results with Cadence Spectre simulation results and Berkeley Design Automation solutions show satisfactory agreement, and underline importance of large-signal assumptions together with proper stability analysis.