STW81102ATR STMicroelectronics, STW81102ATR Datasheet - Page 20

• Manufacturer Part Number: STW81102ATR
• Description: IC SYNTHESIZER MULTI RF 28VFQFPN
• Manufacturer: STMicroelectronics
• Type: Frequency Synthesizerr

Specifications of STW81102ATR

• Pll: Yes
• Input: Clock, Crystal
• Output: Clock, Crystal
• Number Of Circuits: 1
• Ratio - Input:output: 3:2
• Differential - Input:output: No/No
• Frequency - Max: 4.65GHz
• Divider/multiplier: Yes/No
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 28-VFQFN, 28-VFQFPN
• Frequency-max: 4.65GHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Circuit description
5.4
20/53
A and B counters
The 5-bit A-counter and 12-bit B-counter, in conjunction with the selected dual modulus
(16/17 or 19/20) prescaler, make it possible to generate output frequencies which are
spaced only by the reference frequency divided by the reference division ratio. Thus, the
division ratio and the VCO output frequency are given by these formulas:
N
where:
For a correct working of the VCO divider, B must be strictly higher than A. A can take any
value ranging from 0 to 31. The range of N can vary from 256 to 65551 (P=16) or from 361
to 77836 (P=19).
Figure 16. VCO divider diagram
F
VCO
VCOBUF+
VCOBUF-
=
F
P: modulus of dual modulus prescaler (16 or 19 selected through the digital interface)
B: division ratio of the main counter
A: division ratio of the swallow counter
F
R: division ratio of reference counter
N: division ratio of PLL
B
ref
VCO
×
=
: input reference frequency
P
(
-------------------------------------------------- -
: output frequency of VCO
B
+
×
A
P
+
R
A
)
×
F ref
16/17 or 19/20
Prescaler
A-counter
5-bit
modulus
B-counter
12-bit
To PFD
STW81102