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| MLX71121_15 Datasheet, PDF (15/29 Pages) Melexis Microelectronic Systems – FSK/OOK Receiver | |||
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MLX71121
300 to 930MHz
FSK/OOK Receiver
2.2 Calculation of Frequency Settings
The receiver has two predefined receive frequency plans which can be selected by the RFSEL control pin.
Depending on the logic level of RFSEL pin the sideband selection of the second mixer and the counter set-
tings for N1 and N2 are changed accordingly.
RFSEL
Injection
fRFmin [MHz]
fRFmax [MHz]
N1
N2
0
high-low
300
470
4
6
1
low-high
610
930
2
12
The following table shows the relationships of several internal receiver frequencies for the two input frequen-
cy ranges.
fRF [MHz]
300 to 470
610 to 930
fIF1
f RF ï« N1f IF2
N1 ï1
f RF ï N1f IF2
N1 ï«1
fLO1
N1 (fRF ï« f IF2 )
N1 ï1
N1 (fRF ï« f IF2 )
N1 ï«1
fLO2
f RF ï« f IF2
N1 ï1
f RF ï« f IF2
N1 ï«1
fRO
f RF ï« f IF2
N2 (N1 ï1)
f RF ï« f IF2
N2 (N1 ï« 1)
Given IF2 = 1.8MHz and the corresponding N1, N2 counter settings, above equations can be transferred into
the following table.
fRF [MHz]
300 to 470
610 to 930
fIF1
f RF ï« 7.2MHz
3
fRF ï 3.6MHz
3
fLO1
4(f RF ï« 1.8MHz )
3
2(f RF ï« 1.8MHz )
3
fLO2
f RF ï« 1.8MHz
3
fRO
f RF ï« 1.8MHz
18
f RF ï« 1.8MHz
36
39010 71121
Rev. 012
Page 15 of 29
Data Sheet
Mar/15
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