ATR4258 Datasheet, PDF (29/38 Pages) ATMEL Corporation – AM/FM RECEIVER IC

ATR4258
Application Information
AM Prescaler (Divider)
Settings
The AM mixer is used for up conversion of the AM reception frequency to the IF fre-
quency. Therefore an AM prescaler is implemented to generate the necessary LO from
the VCO frequency. For the reception of the AM band different prescaler (divider) set-
tings are possible.
Table 37 gives an example for the AM prescaler (divider) settings and the reception
frequencies.
e.g.,
f_VCO = 98.2 MHz ... 124 MHz
f_IF = 10.7 MHz
f_rec
=
⎛
⎝
A^----M^-------P^-f--V-r^--e^C---s^-O---c^--a^----l^-e^----r^⎠⎞
– f_IF
Table 37. AM Prescaler (Divider) Settings and Reception Frequencies
Minimum Reception Frequency Maximum Reception Frequency
Divider (AM Prescaler)
[MHz]
[MHz]
divide by 2
38.4
51.3
divide by 3
20.033
30.633
divide by 4
13.85
20.3
divide by 5
8.94
14.1
divide by 6
5.667
9.967
divide by 7
3.329
7.014
divide by 8
1.575
4.8
divide by 9
0.211
3.078
divide by 10
0
1.7
Note: Prescaler VCO Divider = 1 in this example.
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4838A–AUDR–10/04