Block Diagram

Functional Description

The TDA1574 is an integrated monolithic FM tuner for use in the RF / IF part of car radios and home receivers. lt

contains all function units for a complete VHF tuner with exception of a RF stage.

The following sections are integrated:

• mixer

• oscillator inclusive buffer stages and a measuring output

• linear IF amplifier

• standby switch

• reference voltage source

• control voltage generation

VOLTAGE

STABILIZER

n1

+V

CC

10

STAND BY

SWITCH

=

~

~

~

DOUBLE BALANCED

MIXER

-

+

-

+

+

-

+

-

-

+

-

+

10 n

82 p

5.5

5.5

n2

68

300

R

ML

V

aM

MIXER OUTPUT

VOLTAGE

AGC

NARROW BAND

INFORMATION

TUNER

ON

OFF

IF INPUT

V

iIF

22 n

22 n

22 n

300

IF OUTPUT

VOLTAGE

V

aIF

10 n

1 n

75

BUFFERED

OSCILLATOR

OUTPUT

R

g2

1 1/4

3 1/4

3.9 p

30 p

n2

n1

n2

n1

1 n

50

(98 MHz)

~

~

~

V

e2HF

for AGC

6.8 p

6.8 p

56 p

56 p

14

50

R

g1

(98 MHz)

V

e1HF

22 n

100

OUTPUT

AGC

18

17

16

15

12

11

14

13

10

5

9

8

7

6

4

3

2

1

++

50

µA

+

0.5 V

10 k

+

1.7V

200

AGC-VOLTAGE

GENERATION

14

14

HF INPUT

OSCILLATOR

OSCILLATOR

OUTPUT BUFFERS

950

4.1 V

V

ref

V

p

300

300

IF AMPLIFIER

V

p

IF OUTPUT

TDA 1574

2

09/00

TDA1574