EVB71120
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
0
1
Injection
high-low
low-high
f
RFmin
[MHz]
300
610
f
RFmax
[MHz]
470
930
N
1
4
2
N
2
6
12
The following table shows the relationships of several internal receiver frequencies for the two input
frequency ranges.
f
RF
[MHz]
300 to 470
f
IF1
f
LO1
f
LO2
f
RO
f
RF
+
N
1
f
IF2
N
1
−
1
N
1
(f
RF
+
f
IF2
)
N
1
−
1
f
RF
+
f
IF2
N
1
−
1
f
RF
+
f
IF2
N
2
(N
1
−
1)
610 to 930
f
RF
−
N
1
f
IF2
N
1
+
1
Given IF2 is selectable at either 455kHz or 10.7MHz and the corresponding N
1
, N
2
counter settings, above
equations can be transferred into the following table.
IF2=455kHz
f
RF
[MHz]
300 to 470
f
RF
+
1.82MHz
3
f
RF
−
0.91MHz
3
610 to 930
IF2=10.7MHz
f
RF
[MHz]
300 to 470
Y
R
A
IN
IM
L
E
R
P
f
IF1
f
LO1
f
LO2
f
RO
N
1
(f
RF
+
f
IF2
)
N
1
+
1
f
RF
+
f
IF2
N
1
+
1
f
RF
+
f
IF2
N
2
(N
1
+
1)
4(f
RF
+
0.455MHz )
3
2(f
RF
+
0.455MHz )
3
f
RF
+
0.455MHz
3
f
RF
+
0.455MHz
18
f
RF
+
0.455MHz
36
f
IF1
f
LO1
f
LO2
f
RO
f
RF
+
42.8MHz
3
f
RF
−
21.4MHz
3
4(f
RF
+
10.7MHz )
3
2(f
RF
+
10.7MHz )
3
610 to 930
f
RF
+
10.7MHz
3
f
RF
+
10.7MHz
18
f
RF
+
10.7MHz
36
39012 71120 01
Rev. 003
Page 7 of 18
EVB Description
Jan/08
MELEXIS [ Melexis Microelectronic Systems ]
