2.6.1 RF_N_CNTR (RF_N[28]-[14])

The RF N counter value is determined by three counter values that work in conjunction with four prescalers. This quadruple

modulus prescaler architecture allows lower minimum continuous divide ratios than are possible with a dual modulus prescaler

architecture. For the determination of the A, B, and C counter values, the fundamental relationships are shown below.

N=PC+4B+ A

C

≥ max {A,B} + 2

The A, B, and C values can be determined as follows:

C=N div P

B=(N-CP) div 4

A = (N - CP) mod 4

N REGISTER FOR THE CELLULAR (8/9/12/13) PRESCALER OPERATING IN FRACTIONAL MODE

Divide

RF_N_CNTR [14:0]

Ratio

C Word

B Word

A Word

1-23

Divide Ratios Less than 24 are impossible since it is required that C

≥ 3

24-39

Some of these N values are Legal Divide Ratios, some are not

40

00000000101

0000

41

00000000101

0001

…

...........

0

.

.

.

16383

11111111111

0111

N REGISTER FOR THE PCS (16/17/20/21) PRESCALER OPERATING IN FRACTIONAL MODE

Divide

RF_N_CNTR [14:0]

Ratio

C Word

B Word

A Word

1-47

Divide Ratios Less than 48 are impossible since it is required that C

≥ 3

48-79

Some of these N values are Legal Divide Ratios, some are not

80

00000000101

0000

81

00000000101

0001

…

...........

0

.

.

.

32767

11111111111

1111

2.6.2 FRAC_N (RF_N[13]-[10])

These four bits, the fractional accumulator modulus numerator, set the fractional numerator values in the fraction.

Modulus Numerator

FRAC_N [3:0]

0

0000

1

0001

2

0010

•

••••

14

1110

15

1111

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