SiTime mentioned above is selling oscillators that can be embedded in the same package as the microcontroller. I would say that's the way to go.
I wonder how SiLabs compares to the competition? Personally, I tend to favor MEMS platforms based on SOI that are DRIE:d into the structures. Mostly due to the simplicity and the use of monocrystalline Si. SiLabs deposit a pretty thick layer of poly-SiGe (SiGe can be deposited at pretty low temperatures which is critical if CMOS-wafers are the substrate that is deposited) that is formed into the resonator structure.
Guess in the end it's a question about the yield of the processes.
The 2mm x 2.5mm size is nice. It's disappointing how large a lot of the current oscillators are compared to the tiny chips around them. Sometimes the oscillator is bigger than the MCU.
My next question is, when can I get these integrated with the MCU on the same dice?
As we unveil EE Times’ 2015 Silicon 60 list, journalist & Silicon 60 researcher Peter Clarke hosts a conversation on startups in the electronics industry. Panelists Dan Armbrust (investment firm Silicon Catalyst), Andrew Kau (venture capital firm Walden International), and Stan Boland (successful serial entrepreneur, former CEO of Neul, Icera) join in the live debate.