DS_S1M8837 Datasheet, PDF (24/29 Pages) Samsung semiconductor – FRACTIONAL-N RF/INTEGER-N IF DUAL PLL

S1M8836/37
FRACTIONAL-N RF/INTEGER-N IF DUAL PLL
PULSE SWALLOW FUNCTION
The RF VCO′ frequency fVOC becomes NINT + NFRAC times the comparison frequency(fOSC/R) where
NINT is the integer divide ratio and NFRAC is the fractional component;
fVCO = (NINT + NFRAC) × fOSC/R = N × fOSC/R
where NINT = P × B + A
RF PLL: NFRAC = F/62976, -31488 ≤ F ≤ 31488, and R = 1, 2, 3 (typically 2)
IF PLL: NFRAC = 0, B > A and 3 ≤ R ≤ 32767
fVCO: External VCO output frequency
fOSC: External reference frequency(From external oscillator)
R: Preset divide ratio of programmable R counter (RF: 1, 2, 3(typically 2), IF: 3 to 32767);
P: Preset modulus of quadruple modulus prescaler (S1M8836 RF:P=8, S1M8837 RF:P=16, IF:P=8)
B: Preset value of main counter (S1M8836/37 RF: 3 to 127, IF: 3 to 4095)
A: Preset value of swallow counter division ratio
(S1M8836 RF: 0 ≤ A ≤ 7, S1M8837 RF: 0 ≤ A ≤ 15. IF: 0 ≤ A ≤ 7, A<B)
NFRAC: Fractional component of Pulse-swallowed division ratio N (for IF: NFRAC = 0)
F: Preset value of fractional register(-31488 ≤ F ≤ 31488 ); For a negative integer, F should be inputted as its 2's
complementary binary code.
For examples in S1M8836 fractional-N mode (fOSC=19.68MHz, R=2, P=8)
1) for fvco = 955.02MHz; N = 97.05487805, B=12, A=1, F=3456 (= 0 0000 1101 1000 0000)
2) for fvco = 955.03MHz; N = 97.05589431, B=12, A=1, F=3520
3) for fvco = 956.25MHz; N = 97.17987805, B=12, A=1, F=11328
4) for fvco = 979.35MHz; N = 99.52743902, B=12, A=4, F=-29760
For examples in S1M8837 fractional-N mode (fosc=19.68MHz, R=2, P=16)
1) for fvco = 1620.87MHz(CH25) ; N = 164.722561, B=10, A=5, F=-17472 (= 1 1011 1011 1100 0000)
2) for fvco = 1620.88MHz
; N = 164.7235772, B=10, A=5, F=-17408
3) for fvco = 1622.12MHz(CH50) ; N = 164.8495935, B=10, A=5, F=-9472
4) for fvco = 1632.12MHz(CH250) ; N = 165.8658537, B=10, A=6, F=-8448
5) for fvco = 1648.37MHz(CH575) ; N = 167.5172764, B=10, A=8, F=-30400
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