xr215a Exar Corporation, xr215a Datasheet - Page 19

• Manufacturer Part Number: xr215a
• Description: Monolithic Phase-locked Loop
• Manufacturer: Exar Corporation

APPLICATIONS INFORMATION
FM Demodulation
Figure 16 shows the external circuit connections to the XR-215A for frequency-selective FM demodulation. The choice
of C
selectivity requirements. For carrier frequencies of 1 to 10MHz, C
resistor R
demodulated output amplitude is proportional to the FM deviation and to resistors R
be approximated as:
where all resistors are in k and R
below 5MHz, R
Typical output signal/noise ratio and harmonic distortion are shown in Figure 17 and Figure 18 as a function of FM
deviation, for the component values shown in Figure 5.
0
Rev. 1.01
is determined by the FM carrier frequency (see Figure 8. ) The low-pass filter capacitor C
F
can be used as a “volume-control” adjustment to set the amplitude of the demodulated output. The
X
can be omitted. For operation above 5MHz, R
FM
Input
Cc
R
x
Figure 16. Circuit Connection for FM Demodulation
R
X
0
is the range extension resistor connected across pins 9 and 10. For circuit operation
U1
11
12
10
6
V
9
2K
V
EE
OUT
13
C
0.1 F
Phase
Comp.
0
5K
R
14
0
R
C
F
1
5
1
2
19
50
C
5K
1
+12V
3
16 V
0.6
R
50
1
X
XR-215A
X
Op
Amp
R
P
CC
1
mV , rms
10K
7
750
0.1 F
300pF
is in the range of 10 C
2K
15
4
8
Cc Coupling Capacitor
R
is recommended.
F
2K
Volume
Control
0
7.5K
and R
8K
Cc
F
for +1% FM deviation it can
0
10nF (De-Emphasis)
to 30 C
XR-215A
1
is determined by the
Demodulated
Output
0
. The feedback