A MEMS-Based GPS-Disciplined Oscillator for Mobile RF Measurement Applications

Many spatially distributed radio frequency (RF) measurement setups require coherence, i.e., synchronization of their local oscillators (LOs). In static setups, this can be achieved by distributing a common reference clock signal over a wired cable infrastructure. In mobile setups without wired infrastructure, synchronization can be achieved using global positioning system (GPS)-disciplined oscillators (GPSDOs). However, those typically incorporate rather bulky crystal oscillators, which are inherently sensitive to mechanical stress, i.e., vibration and temperature fluctuation. In contrast, micro-electromechanical system (MEMS) oscillators are less sensitive to environmental influences, while maintaining a small footprint. This paper presents a compact MEMS-based GPSDO concept with real-time kinematic (RTK) support for mobile applications. Measurements for short-and long-term frequency stability of the fabricated design are shown.