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| EVB71121 Datasheet, PDF (7/18 Pages) Melexis Microelectronic Systems – 300 to 930MHz Receiver Evaluation Board Description | |||
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EVB71121
300 to 930MHz Receiver
Evaluation Board Description
2.1 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
settings for N1 and N2 are changed accordingly. (see in 1.5)
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
frequency ranges.
fRF [MHz]
300 to 470
fIF1
f RF + N1f IF2
N1 â1
fLO1
N1 (f RF + f IF2 )
N1 â1
fLO2
f RF + f IF2
N1 â1
fRO
f RF + f IF2
N 2 (N1 â 1)
610 to 930
f RF â N1f IF2
N1 (f RF + f IF2 )
f RF + f IF2
f RF + f IF2
N1 +1
N1 +1
N1 +1
N 2 (N1 + 1)
PRELIMINARY 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
fRF + 7.2MHz
3
fRF â 3.6MHz
3
fLO1
4(fRF + 1.8MHz)
3
2(fRF + 1.8MHz)
3
fLO2
fRF + 1.8MHz
3
fRO
fRF + 1.8MHz
18
fRF + 1.8MHz
36
39012 71121 01
Rev. 003
Page 7 of 18
EVB Description
Jan/08
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