micrf405 Micrel Semiconductor, micrf405 Datasheet - Page 26

• Manufacturer Part Number: micrf405
• Description: Micrf405 290mhz To 980mhz Ism Band Ask/fsk Transmitter
• Manufacturer: Micrel Semiconductor

April 2006
The design of the PLL filter will strongly affect the
performance of the frequency synthesizer. Input
parameters, when designing the loop filter for the
MICRF405, are mainly the modulation method and
the bit rate. Internal loop filter, which have relative
Modulation
Open loop
Open loop
>9.6kbps
≤4.8kbps
≤9.6kbps
VCO
VCO
type
ASK
ASK
ASK
Fphd
[kHz]
1000
1000
2000
2000
500
[kHz]
22.5
BW
220
45
32
64
3.125/31.25
3.125/31.25
6.25/62.5
6.25/62.5
12.5/125
[uA]
CP
Table 18. Internal Dual Path Filter Settings.
CP_CUR
1
2
1
2
3
32.4
32.4
32.4
32.4
[pF]
5.4
C1
26
high bandwidths, is recommended for ASK. The
external filter must be used when the bandwidth
must be low. These choices will also affect the
switching time and phase noise.
[pF]
10.8
10.8
10.8
10.8
1.8
C2
LF_CAP
3
3
3
3
0
[kΩ]
R1
96
48
68
34
76
LF_RES1
7
2
4
1
5
[kΩ]
R3
57
28
40
20
5
[phone]
M9999-041906
LF_RES3
8
3
5
2
0