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low distortion compression limiting
38dB maximum system gain, adjustable over a
38dB range
output compression threshold, adjustable over
16dB range
designed to drive a class D integrated receiver
averaging detector
additional gain stage
DESCRIPTION
The GR592 features AGC-O capability for low distortion output
limiting. The circuit consists of an AGC preamplifier, an output
stage capable of driving a class D integrated receiver and an
independent gain stage.
The compression control circuit, connected between the input
and output of the AGC preamplifer, varies the current
controlled resistance. It operates with an 8:1 compression
ratio and uses an averaging detector. The time constant of
the detector is a function of the rectifier capacitor value. With
the rectifier capacitor value 150nF the time constant of the
detector is 270ms, providing optimal sound quality over a full
range of sound and listening environments. The actual attack
and release times are typically 40ms and 150ms respectively
when the circuit is fully in the compression region of operation
(measured times vary depending on gain and threshold
settings).
The system gain and compression control can be adjusted
by choosing two independent resistors or 100k trimmers.
Maximum system gain (AGC preamplifier and the output
stage) is 38dB. The output compression threshold can be
adjusted within a 16dB range.
GR592
PACKAGING
Chip
(94 x 48 x 10 mil)
(2.39 x 1.22 x 0.25 mm)
Au Bump
V
B
4
R
VC
1
R
TH
14
C
AGC
12
V
REG
5
REGULATOR
8:1
COMPRESSION
CONTROL
80k
RECT.
V
B
48k
9
IN
10k
-F
12k
-A
B
13
OUT
48k
7
800
8
6
3
2
11
10
RF4A
RF4B
F
OUT
AIN
A
OUT
RECT
GND
All resistors in ohms, all capacitors
in farads, unless otherwise stated.
BLOCK DIAGRAM
Doc. No. 19423 - 0 [Rev. July 200]
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