Sorry I wasn't clear - the Silabs parts seem to use a very different mechanism than the devices I was warning about. The Silabs parts use a MEMS resonator which is tuned somehow (probably by adjusting the amount of electrostatically-generated tension on the silicon structural beams which are part of the resonator). The tuning is done at the factory and then the part contains temperature compensation and has inherently low ageing. Since it is just an oscillator and not a synthesizer, the jitter is low. The least expensive of the programmable oscillators are PLL-based and can have very significant jitter problems - which matter only for certain applications. Even if their RMS jitter is not too bad, it may be concentrated in very narrow frequency bands and still present a problem for RF applications, for example. Many of the newer PLL-based programmable oscillators use various fancy techniques to reduce jitter, such as intentionally dithering the jitter so that it spreads out more over frequency, or they cancel out the one or two highest jitter spectral peaks. The AD9850 which was mentioned is not a programmable oscillator but a DDS IC. DDS also generates an output with deterministic jitter and has its own set of problems. Many DDS devices also implement fancy corrections to cancel out some of the jitter. I am not casting aspersions on any of these technologies, just warning that you need to pay attention to jitter if it matters to you. For typical digital applications, it doesn't. For high-speed busses and telecoms applications, it often does matter, but not in the same way that it matters to RF applications. I have built radio receivers using both cheap PLL-based programmable oscillators and DDS chips and experienced these problems. They showed up as "birdies" or spurious responses in the receiver. With the DDS chip I was able to get around this by changing the DDS chip settings to shift the spurious outputs for different frequency ranges of the receiver so that they almost always fell outside of the present frequency band. But, the key thing is that one must be aware of the need to consider this problem, which does not arise with a simple oscillator. Sean On Sat, Oct 11, 2014 at 12:20 AM, Jean-Paul Louis wrote: > Sean, > > This one (SI501) has a spec about jitter. See Page 6 of the data sheet. > The device is specified as less than 26ps cycle to cycle jitter, > 16ps period jitter, and less than 3.2 ps phase jitter. > > No sure about your requirements, but that part is what I use for a lot of > my clock needs as the unit cost is also great, and the part is very small= .. > > Jean-Paul > AC9GH > > --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .