The first quartz crystal oscillator (XO) was built in 1921 by American physicist and electrical engineer Walter Guyton Cady. The main families include the following: standard crystal oscillator (XO), voltage-controlled crystal oscillator (VCXO), temperature-compensated crystal oscillator (TCXO), oven-controlled crystal oscillator (OCXO), double oven-controlled crystal oscillator (DOCXO), voltage-controlled temperature-compensated crystal oscillator (VCTCXO), voltage-controlled oven-controlled crystal oscillator (VCOCXO), microcomputer-compensated crystal oscillator (MCXO or MXO), and… then things start to get complicated. Today, those same terms are used just as readily to describe MEMS resonators and MEMS-based oscillators. This is where SiTime’s new Titan MEMS resonators come into play. A Titan MEMS resonator (lower left) is much smaller than a quartz resonator (Source: SiTime)This means that the Titan consumes 7X less PCB real estate compared to a 1210-size quartz crystal.