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STW81100

Table 20. A_COUNTER

Bit B0 for B Counter, A Counter value and bit R8 for Reference divider.

Table 21. REF_DIVIDER

Reference Clock divider ratio R[7:0] (bit R8 in the previous register).

The LO output frequency is programmed by setting the proper value for A,B and R according to the fol-

lowing formula:

Table 22. Calibration

This register controls VCO calibrator.

INITCAL: resets the auto-calibrator State Machine (writing to “1” and back to “0”)

SERCAL: at “1” starts the VCO auto-calibration (should be reset to “0” at the end of calibration)

SELEXTCAL: at “1” selects control word EXTCAL[4:0] for the VCO

EXTCAL[4:0]: control word for the VCO

Table 23. CONTROL

The CONTROL register is used to set the VCO output voltage amplitude and the Charge Pump Current.

PLL_A[1:0]: VCO amplitude

CPSEL[2:0]: Charge Pump output current

MSB

LSB

b7

b6

b5

b4

b3

b2

b1

b0

B0

A5

A4

A3

A2

A1

A0

RS

MSB

LSB

b7

b6

b5

b4

b3

b2

b1

b0

R7

R6

R5

R4

R3

R2

R1

R0

1

for Direct Output

0.5

for Output Divided by 2

0.25

for Output Divided by 4

MSB

LSB

b7

b6

b5

b4

b3

b2

b1

b0

INIT CAL

SER CAL

SEL EXT CAL

CAL 0

CAL 1

CAL 2

CAL 3

CAL 4

b7

b6

b5

b4

b3

b2

b1

b0

PLL_A0

PLL_A1

CP SEL 0

CP SEL 1

CP SEL 2

NA

NA

NA

F

OUT

D

R

B64

A

+

⋅

()

F

RE F_CLK

R

--------------------------

⋅⋅

=

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