STW81100 STMicroelectronics, STW81100 Datasheet - Page 19

• Manufacturer Part Number: STW81100
• Description: MULTI-BAND RF FREQUENCY SYNTHESIZER
• Manufacturer: STMicroelectronics

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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
where D
INIT CAL
PLL_A0
MSB
MSB
MSB
B0
R7
b7
b7
b7
b7
R
equals
SER CAL
PLL_A1
b6
b6
R6
A5
b6
b6
{
1
0.5
0.25
SEL EXT CAL
CP SEL 0
for Direct Output
for Output Divided by 2
for Output Divided by 4
A4
R5
b5
b5
b5
b5
F
OUT
=
D
CP SEL 1
R
R4
CAL 0
b4
A3
b4
⋅
b4
b4
(
B 64
⋅
+
CP SEL 2
A
CAL 1
R3
A2
b3
b3
)
b3
b3
⋅
F
--------------------------
REF_CLK
R
CAL 2
A1
R2
b2
b2
NA
b2
b2
CAL 3
R1
b1
A0
b1
NA
b1
b1
STW81100
CAL 4
LSB
LSB
LSB
RS
R0
NA
b0
b0
b0
b0
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