3.2 Output Termination and Optional Buffer
In most applications simple R C termination is used, as seen with R1 and C4 in
Figure 6.1 SiOCXO1-EB Schematic on page 8
. This
is a resistor to optimize impedance matching and a capacitor to block DC. Modifications can be made as required.
Optionally a buffer can be added to minimize loading on the OCXO’s output, such as when driving cables. In this case U2, J6, C7, C8,
R8, and R9 must be populated, while R2 can be depopulated.
3.3 Optional OCXO Frequency Adjust
Some OCXO’s have an optional control voltage to adjust the output frequency, usually by a small amount such as 1 or 2 ppm. One
example would be to discipline the OCXO to reduce the effects of OCXO aging. In this case, J3 and R4 must be populated as a
minimum. C6 can be used for filtering or BW frequency limiting. Alternatively, R5 and C6 could be fixed or adjustable resistors to set a
DC bias voltage.
UG123: SiOCXO1-EVB Evaluation Board User's Guide • Functional Description
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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Rev. 1.1 • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice • July 26, 2021
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