The readily available blank crystal oscillators can be programmed to the customer’s desired timing requirements, if the fixed frequency oscillator is not immediately available. How does it work? The basic principle of the Epson’s newer P-SPXO is using the new Fractional-N PLL technology to synthesize any frequency from 0.67MHz to 170MHz with 1ppm resolution and features no frequency holes, unlike previous generation devices which used integer based PLL.