The introduction of integrated circuits (IC) in the twentieth century changed the way engineers designed electronic systems. In telecommunications, radio frequency (RF) ICs have performance requirements that are not readily or cheaply attainable using commercial IC technologies. Microelectromechanical systems (MEMS) offer the opportunity to integrate many RF subcomponents on-chip, which have traditionally been implemented off-chip. The chapter reviews some conventional transceiver architectures along with their potential for MEMS implementations. It describes MEM resonators in detail from their evolution and applications to their operation and use in systems such as MEM resonator–based filters and arrays. The chapter also reviews case studies of published works involving MEM resonators. Micromechanical resonators are structures that can be used for filtering or frequency synthesis applications in many subcomponents of RF transceivers, due to their high level of frequency selectivity. As MEM resonators are easily integrated, several resonators can be combined to broaden their functionality.