S1M8831A Datasheet, PDF (27/32 Pages) Samsung semiconductor – FRACTIONAL-N RF/INTEGER-N IF DUAL PLL

FRACTIONAL-N RF/INTEGER-N IF DUAL PLL
S1M8831A/33
Pulse Swallow Function
The RF VCO's frequency fVCO 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, B > P, and R = 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: 2, IF: 3 to 32767);
P : Preset modulus of dual modulus prescaler (S1M8831 RF: P=8, S1M8833 RF: P=16, IF: P=8)
B : Preset value of main counter (S1M8831A/33 RF: 3 to 126, IF: 3 to 4095)
A : Preset value of swallow counter division ratio
(S1M8831 RF: 0 ≤ A ≤ 7, S1M8833 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 S1M8831 fractional-N mode (fOSC = 19.68MHz, R=2, P=8)
1) for fvco = 955.02MHz
0000)
; N = 97.05487805, B=12, A=1, F=3456 (= 0 0000 1101 1000
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
∴ F= 0.52743903 X 62976 = 33125 → 33125 > 31488 (A=3+1=4)
= 33215 – 62976 = -29760 (1 1000 1011 1100 0000)
For examples in S1M8833 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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