Multi-technology design of an integrated MEMS-based RF oscillator using a novel silicon-ceramic compound substrate

Abstract

In this paper, an approach towards the realization of a hybrid MEMS-CMOS RF oscillator module using the novel silicon-ceramic (SiCer) compound substrate technology is described. Piezoelectric aluminium-nitride MEMS resonators with quality factors Q up to 2,200 and resonant frequencies of 240, 400 and 600 MHz have been investigated as frequencyselective elements. For RF-compatible hybrid-integrated assembly and packaging, the SiCer compound substrate has been adapted, promising an efficient integration of both, microelectronic and micromechanical devices, on a single carrier substrate. Multiphysical circuit design and simulations using parametrized behavioural MEMS models have been carried out, indicating stable oscillator operation at the design frequency. As one prospective application, such an oscillator module could form part of a compact and power-efficient reconfigurable RF transceiver frontend in SiCer technology, e.g., for mobile communications.

Hybrid-integrated RF MEMS-based reference oscillator using a silicon-ceramic composite substrate

“…The MEMS oscillator introduced in [3] consists of an integrated active circuit and a piezoelectric MEMS resonator on a unique silicon-ceramic (SiCer) composite substrate [4], which is well suited for multi-physical circuit designs. This substrate is constructed in several steps: After preparing a standard low-temperature co-fired ceramic (LTCC) multilayerstructure (including, e.g., vias, wiring, passive elements), a bare silicon wafer is bonded onto the ceramic module by sintering.…”

“…The experience gained from previous measurements on resonators operating at 400 MHz [5] provided important insight into mechanisms determining the Q-factor, since the complex damping mechanisms in the mechanical resonators can hardly be predicted from numerical simulations but need to be supported by empirical values [7]. Eventually the assumption of Q = 1800 was made based on typical measurement values [3].…”