TK10651MTL/10651 Ver la hoja de datos (PDF) - Toko America Inc

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TK10651MTL/10651

LOW VOLTAGE COMPANDOR

Toko America Inc  

TK10651

TYPICAL PERFORMANCE CHARACTERISTICS (CONT.)

THIRD ORDER LPF CHARACTERISTICS

OUTPUT VOLTAGE vs. THIRD

ORDER LPF INPUT FREQUENCY

10

0

-10

-20

-30

-40

-50

-60

-70

0.1 0.2 0.5 1 2 5 10 20 50 100

fIN (kHz)

OUTPUT VOLTAGE VS. THIRD

ORDER LPF INPUT VOLTAGE

0

VCC = 3.0 V

fIN = 1.0 kHz

-10

-20

-30

-40

-50

-60

-70

-90 -80 -70 -60 -50 -40 -30 -20 -10 0

VIN (dBV)

USING THE COMPANDOR TO IMPROVE S/N

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 ±3.0 kHz frequency

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.

TEST CONFIGURATION

TK10651

FM

COMP

SG

FM IF IC

TK10487

TK10651

EXP

V

MODULATION LEVEL vs.

COMPRESSOR INPUT

7

VCC = 3.0 V

6

fMOD = 1.0 kHz

5

4

COMPRESSOR

3

2

THROUGH

1

0

0.1 0.2 0.5 1 2 5 10 20 50 100

VIN (mVrms)

January 2000 TOKO, Inc.

Page 7

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