FUNCTIONAL BLOCK DIAGRAM

SIGNAL

OUT

CURRENT

MIRRORS

V+

V+

V+

SIGNAL

INPUT

36k

Ω

36k

Ω

V+

V–

REV. C

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use, nor for any infringements of patents or other rights of third parties

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a

Dynamic Range

Processors/Dual VCA

SSM2120/SSM2122

© Analog Devices, Inc., 1995

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 617/329-4700

Fax: 617/326-8703

GENERAL DESCRIPTION

The SSM2120 is a monolithic integrated circuit designed for the

purpose of processing dynamic signals in various analog systems

including audio. This “dynamic range processor” consists of two

VCAs and two level detectors (the SSM2122 consists of two

VCAs only). These circuit blocks allow the user to logarithmically

control the gain or attenuation of the signals presented to the

level detectors depending on their magnitudes. This allows the

compression, expansion or limiting of ac signals, some of the

primary applications for the SSM2120.

FEATURES

0.01% THD at +10 dBV In/Out

100 dB VCA Dynamic Range

Low VCA Control Feedthrough

100 dB Level Detection Range

Log/Antilog Control Paths

Low External Component Count

APPLICATIONS

Compressors

Expanders

Limiters

AGC Circuits

Voltage-Controlled Filters

Noise Reduction Systems

Stereo Noise Gates

PIN CONNECTIONS

22-Pin Plastic DIP

(P Suffix)

16-Pin Plastic DIP

(P Suffix)

13

16

15

14

22

21

20

19

18

17

12

TOP VIEW

(Not to Scale)

11

10

9

8

1

2

3

4

7

6

5

SSM2120

THRESH 1

V+

GND

LOG AV 1

CFT 2

CFT 1

LOG AV 2

V–

THRESH 2

14

13

12

11

16

15

10

9

8

1

2

3

4

7

6

5

TOP VIEW

(Not to Scale)

SSM2122

GND

V+

GND

CFT 1

CFT 2

V–

GND