LOW VOLTAGE/POWER NARROW BAND FM IF
KA3361C
APPLICATION CIRCUIT
Mixer input
10.7MHz
51Ω
10nF
16
MIXIN
15
GND
Audio
Mute
Scan
Control
Squelch
SW input
10kΩ
Audio
Filter
Filter
Amp out Amp in output
1.0uF
510kΩ
470kΩ
8.2kΩ
9
AUDIO
10nF
1.0uF
14
MUTE
13
SCAN
12
SQ
11
FOUT
10
FIN
KA3361C
OSC
1
OSC MIXOUT VCC
2
3
455MHz
Filter
4
LIMIN DECOLP LING
5
6
7
QUAD
8
68pF
10.24MHz 220pF
20kΩ
0.1uF
0.1uF
Quad coil
Vcc
0.1uF
In the above typical application, the audio signal is recovered using a conventional quadrature FM detector. The
bsence of an input signal is indicated by the presence of noise above the desired audio frequencies. This
“noise
band” is monitored by an active filter and a detector. A squelch trigger circuit indicates the presence of noise (or a
tone) by an output which can be used to control scanning. At the same time, an internal switch is operated which
can be used to mute the audio.
5
SAMSUNG [ SAMSUNG SEMICONDUCTOR ]
