Programmable Clock Oscillators Provide the Right Reference Clock, Every Time by SiTime


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									         Programmable Clock Oscillators Provide the Right Reference Clock, Every Time

A reference clock oscillator in electronics has long been the domain of fixed-frequency devices. These
devices have historically consisted of a quartz crystal, which has been cut and manufactured to operate
at a precise, fixed frequency, married to an analog oscillator circuit, which operates at the same fixed
frequency and a fixed voltage. The process of manufacturing these fixed-frequency oscillators has been
optimized over time, and results in accurate clocking devices that are very inflexible in offering features.

With recent advances in semiconductor-based MEMS technology and analog circuits, these fixed
frequency clock oscillators are rapidly being replaced by a programmable clock oscillator.
Programmable clock oscillators use a fixed frequency MEMS resonator, married with a programmable
analog circuit which can offer a host of features that are not available from fixed-frequency oscillators,
such as

        Any frequency within the operating range, achievable by using a highly accurate Phase Locked
        Loop (PLL) which can multiply the MEMS resonator frequency up to any desired frequency of
        operation. The output frequency is accurate up to 6 decimal places of accuracy (1 Hz). This is
        particularly useful in applications where non-standard frequencies are desired to improve
        performance and reduce error rates.
        Ability to operate at any voltage between 2.5V and 3.3V, as well as 1.8V, which are the most
        common input-output voltages used in electronics.
        Programmable drive strength control using SoftEdge technology, which allows the user to
        accurately match the output impedance of the clock oscillator with the trace impedance of the
        board, and thus reduces reflections. Higher drive strength can also be used for driving multiple
        loads, while lower drive strength can be used for reducing electromagnetic interference (EMI).
        Ability to configure the output control pin into Output Enable or Standby

In the case of more-featured oscillators such as Voltage Controlled Oscillators (VCXOs) and Voltage-
Controlled, Temperature Compensated Oscillators (VC TCXOs), the programmability of the device also
allows easy configuration of the pull range.

With such a host of features available from programmable clock oscillators, it is no surprise that the
devices are rapidly gaining in popularity and have already replaced a significant number of fixed
frequency reference oscillators.

Learn more about: - Silicon Oscillator , Crystal Oscillator, Clock Oscillator & MEMS Oscillator

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