STW81100AT-1 STMicroelectronics, STW81100AT-1 Datasheet - Page 12

• Manufacturer Part Number: STW81100AT-1
• Description: IC SYNTHESIZER MULTI RF 28VFQFPN
• Manufacturer: STMicroelectronics
• Type: Frequency Synthesizerr

Specifications of STW81100AT-1

• Pll: Yes
• Input: Clock, Crystal
• Output: Clock, Crystal
• Number Of Circuits: 1
• Ratio - Input:output: 3:2
• Differential - Input:output: No/No
• Frequency - Max: 4.4GHz
• 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: 4.4GHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

STW81100
where:
For a correct work of the VCO divider, B must be strictly higher than A. A can take any value ranging from
0 to 63. The range of the N number can vary from 4096 to 32767.
Figure 13. VCO Divider Diagram
7.5 Phase frequency detector (PFD)
The PFD takes inputs from the reference and the VCO dividers and produces an output proportional to
the phase error. The PFD includes a delay gate that controls the width of the anti-backlash pulse. This
pulse ensures that there is no dead zone in the PFD transfer function.
Figure 14
Figure 14. PFD Diagram
12/29
– FVCO: output frequency of VCO.
– P: modulus of dual modulus prescaler.
– B: division ratio of the main counter.
– A: division ratio of the swallow counter.
– Fref: input reference frequency.
– R: division ratio of reference counter.
– N: division ratio of PLL
is a simplified schematic of the PFD.
VCOBUF+
VCOBUF+
VCOBUF-
VCOBUF-
VDD
VDD
Fref
Fref
VDD
VDD
Fref
Fref
A counter
A counter
Prescaler
Prescaler
64/65
64/65
6 bit
6 bit
D FF
D FF
D FF
D FF
R
R
modulus
modulus
R
R
Delay
Delay
ABL
ABL
Down
Down
Up
Up
B counter
B counter
9 bit
9 bit
To PFD
To PFD