TK10651MTL TOKO, TK10651MTL Datasheet - Page 7

• Manufacturer Part Number: TK10651MTL
• Description: LOW VOLTAGE COMPANDOR
• Manufacturer: TOKO

USING THE COMPANDOR TO IMPROVE S/N
THIRD ORDER LPF CHARACTERISTICS
This section provides an example of using the compandor
to improve S/N in a narrow band FM communication
system. In the test configuration below, the compressor
modulation level was measured as a function of the input
voltage to demonstrate the improvement resulting from the
use of the compressor. An audio signal is connected into
the compressor and the output is measured with the
modulation meter connected to the external modulation
input of the FM signal generator. The compressor's refer-
ence input level was set to produce
deviation. As shown in the graph on the right, the peak
deviation remains the same when the compressor is used,
but a wider input range is obtained. The built-in character-
istics of the IDC circuit limit the maximum frequency devia-
tion to 4.5 kHz.
January 2000 TOKO, Inc.
TK10651
COMP
-10
-20
-30
-40
-50
-60
-70
10
0.1 0.2 0.5 1
0
TEST CONFIGURATION
ORDER LPF INPUT FREQUENCY
TYPICAL PERFORMANCE CHARACTERISTICS (CONT.)
OUTPUT VOLTAGE vs. THIRD
FM
SG
f IN (kHz)
2
5
TK10487
FM IF IC
10 20 50
3.0 kHz frequency
100
TK10651
EXP
V
-10
-20
-30
-40
-50
-60
-70
7
6
5
4
3
2
1
0
0
-90
0.1 0.2 0.5 1
-80 -70 -60 -50 -40 -30 -20 -10
OUTPUT VOLTAGE VS. THIRD
ORDER LPF INPUT VOLTAGE
COMPRESSOR
MODULATION LEVEL vs.
f IN = 1.0 kHz
V CC = 3.0 V
COMPRESSOR INPUT
V IN (mVrms)
V IN (dBV)
2
f MOD = 1.0 kHz
V CC = 3.0 V
5
10 20 50 100
THROUGH
TK10651
0
Page 7