Si4430/31/32-B1
Rev 1.1
25
3.5. Frequency Control
For calculating the necessary frequency register settings it is recommended that customers use Silicon Labs
Wireless Design Suite (WDS) or the EZRadioPRO Register Calculator worksheet (in Microsoft Excel) available on
the product website. These methods offer a simple method to quickly determine the correct settings based on the
application requirements. The following information can be used to calculated these values manually.
3.5.1. Frequency Programming
In order to receive or transmit an RF signal, the desired channel frequency, f
carrier
, must be programmed into the
Si4430/31/32. The Si4431/32 and Si4430 cover different frequencies. This section discusses the frequency range
covered by all EZRadioPRO devices. Note that this frequency is the center frequency of the desired channel and
not an LO frequency. The carrier frequency is generated by a Fractional-N Synthesizer, using 10 MHz both as the
reference frequency and the clock of the (3
rd
order) 敚 modulator. This modulator uses modulo 64000
accumulators. This design was made to obtain the desired frequency resolution of the synthesizer. The overall
division ratio of the feedback loop consist of an integer part (N) and a fractional part (F).In a generic sense, the
output frequency of the synthesizer is as follows:
The fractional part (F) is determined by three different values, Carrier Frequency (fc[15:0]), Frequency Offset
(fo[8:0]), and Frequency Deviation (fd[7:0]). Due to the fine resolution and high loop bandwidth of the synthesizer,
FSK modulation is applied inside the loop and is done by varying F according to the incoming data; this is
discussed further in "3.5.4. Frequency Deviation" on page 27. Also, a fixed offset can be added to fine-tune the
carrier frequency and counteract crystal tolerance errors. For simplicity assume that only the fc[15:0] register will
determine the fractional component. The equation for selection of the carrier frequency is shown below:
The integer part (N) is determined by fb[4:0]. Additionally, the output frequency can be halved by connecting a ?
divider to the output. This divider is not inside the loop and is controlled by the hbsel bit in "Register 75h.
Frequency Band Select." This effectively partitions the entire 240960 MHz frequency range into two separate
bands: High Band (HB) for hbsel = 1, and Low Band (LB) for hbsel = 0. The valid range of fb[4:0] is from 0 to 23. If
a higher value is written into the register, it will default to a value of 23. The integer part has a fixed offset of 24
added to it as shown in the formula above. Table 12 demonstrates the selection of fb[4:0] for the corresponding
frequency band.
After selection of the fb (N) the fractional component may be solved with the following equation:
fb and fc are the actual numbers stored in the corresponding registers.
Add R/W Function/Description
D7
D6
D5
D4
D3
D2
D1
D0   POR Def.
73   R/W
Frequency Offset 1
fo[7]
fo[6]
fo[5]
fo[4]
fo[3]
fo[2]
fo[1]   fo[0]
00h
74   R/W
Frequency Offset 2
fo[9]   fo[8]
00h
75   R/W   Frequency Band Select
sbsel
hbsel
fb[4]
fb[3]
fb[2]
fb[1]   fb[0]
35h
76   R/W
Nominal Carrier
Frequency 1
fc[15]
fc[14]
fc[13]
fc[12]
fc[11]
fc[10]
fc[9]   fc[8]
BBh
77   R/W
Nominal Carrier
Frequency 0
fc[7]
fc[6]
fc[5]
fc[4]
fc[3]
fc[2]
fc[1]   fc[0]
80h
)
(
10
F
N
MHz
OUT
)
(
)
1
(
10
F
N
hbsel
MHz
carrier
)
64000
]
0
:
15
[
24
]
0
:
4
[
(
*
)
1
(
*
10
fc
fb
hbsel
MHz
TX
+
+
+
=
64000
*
24
]
0
:
4
[
)
1
(
*
10
]
0
:
15
[
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
?/DIV>
-
-
+
=
fb
hbsel
MHz
f
fc
TX
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
4432-T-B1C470 |
制造商:Silicon Laboratories Inc 功能描述:One antenna Tx/Rx test card 470MHz |
4432-T-B1C915 |
制造商:Silicon Laboratories Inc 功能描述:One antenna Tx/Rx test card 915MHz |
4432W-1"x72yd |
功能描述:膠帶 70002457219 4432W YDA WHITE 1 IN X 72 YD BULK RoHS:否 制造商:3M Electronic Specialty 產(chǎn)品:Tapes 類型:Shielding 描述/功能:EMI/RFI Foil Shielding Tape 顏色: 材料:Copper Foil 寬度:1 in x 18 yds |
4432W-1/2"x72yd |
功能描述:膠帶 4432WYDA WHITE 1/2X72YD BULK RoHS:否 制造商:3M Electronic Specialty 產(chǎn)品:Tapes 類型:Shielding 描述/功能:EMI/RFI Foil Shielding Tape 顏色: 材料:Copper Foil 寬度:1 in x 18 yds |
4432W-1/2X72YD |
制造商:3M Electronic Products Division 功能描述: |