Highly Integrated RF-MEMS Multi-Frequency Oscillator on a Silicon-Ceramic Composite Substrate
The ongoing technical need for miniaturisation and the increasing number of wireless standards and frequency bands implemented in modern radio-frequency (RF) transceiver systems drive the need for highly integrated circuit technologies with high performance. Especially low-phase noise oscillators, which are required at nearly all frequencies in multi-band RF modules, often consist of components using different technologies, e.g., micro-electromechanical systems (MEMS) resonators and microelectronic circuits, usually with one resonator per output frequency. This paper presents the compact implementation of a multi-frequency MEMS oscillator on a silicon-ceramic composite substrate, tailored to the construction of multi-physical RF modules. MEMS devices and microelectronic circuits are fabricated and assembled on opposite sides of the same substrate, in order to nearly halve the substrate area used. The benefits of integrated circuits for switching, frequency doubling, and dividing increase the scope of functions by keeping the module size nearly constant. This results in a highly integrated oscillator module with optimised phase-noise performance.