2.3
The Calculations
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Software Setup
The right side of the main control screen shows the system setup calculations.
•
FREF is the reference oscillator frequency in MHz.
•
Fref_Frac is not used.
•
RDIV is the number the reference frequency is divided by to get Fpfd.
•
NDIV is the number the output frequency is divided by to get Fpfd.
•
A and B are the variables in the equation Fout = Fpfd (A+PB) as discussed in the prescalar section of
the controls. See Appendix A.
•
Fout is the actual frequency out.
•
Fvco 1x is the undivided frequency out of the VCO.
•
Fvco DIV2 is the frequency out of the VCO divided by 2.
•
Fvco DIV4 is the frequency out of the VCO divided by 4.
•
Spur offset is the offset of the phase frequency detector spur.
•
Icp (Rbias) is the actual current of the charge pump. Calculated from [Icp(4.75k)]/Rbias = Icp
actual
.
SLWU056 – June 2008
TRF3762 EVM User's Guide
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