Integrated MEMS oscillator for cellular transceivers

This is the first work to demonstrate a System in Package (SiP) cellular transceiver with integrated frequency reference. The presented transceiver does not require additional quartz crystal (Xtal) based frequency references and hence this allows for the realization of the first modem to rely solely on a MEMS resonator as the frequency source. The transceiver IC designed in a 65 nm CMOS process was initially designed to support a 26 MHz Xtal resonator. In this work the oscillator design was modified to support the use of a 76.8 MHz chip-scale packaged (CSP) MEMS resonator. This paper compares the key performance metrics of a cellular transceiver using a state of the art digitally compensated crystal oscillator (DCXO) versus a MEMS solution (DCMO). First, the results of a side-by-side evaluation for both the DCXO and DCMO are shown. Then we compare these results to the co-packaged fully integrated SiP solution. Based on measurements of the phase noise, start-up time, and error vector magnitude (EVM), we demonstrate the readiness of MEMS resonators to be deployed in integrated cellular transceivers.