AT86RF211SAHW Atmel, AT86RF211SAHW Datasheet - Page 12

• Manufacturer Part Number: AT86RF211SAHW
• Manufacturer: Atmel

Specifications of AT86RF211SAHW

• Lead Free Status / Rohs Status: Compliant

4.1.3
12
0894C–WIRE–11/08
Synthesizer
A high-speed, high-resolution multi-loop synthesizer is integrated. The synthesizer can operate within
two frequency bands: 400 to 480 MHz and 800 to 950 MHz. All channels within these two bands can be
selected by programming registers F0 to F3. All circuitry is on-chip with the exception of the PLL loop fil-
ter. The phase comparison is made thanks to a charge pump topology. The typical charge pump current
is 225 µA.
Figure 4-4.
The PLL loop filter can be designed to optimize the phase noise around the carrier. A few configurations
for the application and channel spacing can be suggested.
Figure 4-5.
Table 4-2.
Data Rate
Low
Medium
High
Synthesizer Loop Filter Schematic
Choosing the Loop Filter Values
PLL Loop Filter Examples
C1
220 pF
560 pF
100 pF
C2
2.2 nF
5.6 nF
1 nF
Pin 41
FILT1
Fref
R1
C1
FILT1
P F D
C H P
C1
&
R1
14.7 kΩ
3.3 kΩ
10 kΩ
C2
VCOIN
C2
R1
Comments
For improvement of
phase noise
Typical
For high modulation rate
VCO
VCOIN
Pin 42
e2v semiconductors SAS 2008
AT86RF211S