Abstract: An ovenized crystal oscillator assembly includes an oscillator package defining a cavity which houses an interposer assembly. The interposer assembly, which can be housed in a recess in the base of the oscillator package, includes a quartz resonator and an interposer with a thin-film heater and temperature sensor. The quartz resonator is connected to the interposer on its edge(s) that is/are mounted to mechanical standoffs which are connected to electrical pads located on the interposer.