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 N
1
and N
2
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 = 1.8MHz and the corresponding N
1
, N
2
counter settings, above equations can be transferred into
the following table.
f
RF
[MHz]
300 to 470
f
IF1
f
LO1
f
LO2
f
RO
f
RF
+
7.2MHz
3
f
RF
−
3.6MHz
3
610 to 930
Y
R
A
IN
IM
L
E
R
P
4(f
RF
+
1.8MHz )
3
2(f
RF
+
1.8MHz )
3
f
RF
+
1.8MHz
3
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)
f
RF
+
1.8MHz
18
f
RF
+
1.8MHz
36
39012 71121 01
Rev. 003
Page 7 of 18
EVB Description
Jan/08
MELEXIS [ Melexis Microelectronic Systems ]
