that4320 THAT Corporation, that4320 Datasheet - Page 15

• Manufacturer Part Number: that4320
• Description: Pre-trimmed Low-voltage Low-power Analog Engine Dynamics Processor Ic
• Manufacturer: THAT Corporation

Document 600045 Rev 04
picked up in the transmission channel will not cause
mis-tracking between the detectors in the encoder
and decoder. The output of this filter feeds the RMS
detector input, which in turn has the same
pre-emphasis network as in the encoder RMS detec-
tor.
earlier, the expansion ratio of a feedforward ex-
pander can be shown to be
reverses the polarity of the control signal relative to
the encoder, and makes this circuit a 2:1 expander.
General Dynamics Processor
Configurations
4320 so applicable to companding noise reduction
systems also qualify it for application to dynamics
processors of all types. This is even more so when
the application must run from battery power. The
4320 is versatile enough to be used as the heart of a
Using the same log based mathematics described
E.R. = 1 + A
OA
The same distinguishing features that make the
2
is configured as a gain-of-one follower. This
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
Tel: [phone]; Fax: [phone]; Web: www.thatcorp.com
Copyright © 2007, THAT Corporation
compressor, expander, noise gate, AGC, de-esser,
frequency-sensitive compressor, and many other dy-
namics processors. It is beyond the scope of this
data sheet to provide specific advice about any of
these functional classes.
reader to THAT’s applications notebooks volumes 1
and 2, which contain many circuits based on
THAT’s other VCAs and RMS level detectors, but are
largely applicable to the 4320 with only minor varia-
tions. Of course, look for more applications infor-
mation aimed specifically at the 4320 in the future.
Where to go from here
processors is a very intricate art: witness the prolif-
eration of first analog, then digital companding sys-
tems, and the many different dynamics processors
available in the market today. In the applications
section of this data sheet, we offer a single example
of a compander as a starting point only. THAT Cor-
poration’s applications engineering department is
ready to assist customers with suggestions for tailor-
ing and extending these basic circuits to meet spe-
cific needs.
The design of compander systems and dynamics
We refer the interested
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