4305-DEMO THAT Corporation, 4305-DEMO Datasheet - Page 11

• Manufacturer Part Number: 4305-DEMO
• Description: Audio Modules & Development Tools Low-Cost Dynamics Processor Demo Board
• Manufacturer: THAT Corporation

Specifications of 4305-DEMO

• Description/function: Audio DSPs
• Operating Supply Voltage: 15 V
• Product: Audio Modules
• For Use With/related Products: THAT4305
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Document 600067 Rev 01
feedback compressor with a threshold adjustment
(T
the sidechain gain (k), and a make-up gain adjust-
ment (A
the detector level is based on the compressor’s
output.
the threshold setting,
In
dB
Figure 14. Feedback compressor with threshold (T),
), a threshold (the ideal diode), a means to vary
dB
In Figure 14, we have again extended the basic
Once again we start with
Out
For output signals above the level determined by
Out
So for signals above the threshold,
G
dB
dB
dB
dB
= −k (Out
) just as in Figure 8. However, in this case,
= In
> T
gain (A), and ratio (k) adjustments
G
A
dB
dB
S
dB
dB
.
+ G
dB
− T
dB
-k
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THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
dB
) + A
Diode
Ideal
dB
.
RMS
T
S
dB
Out
+
-
dB
Out
dB
threshold setting, the signal at the output of the ideal
diode threshold is 0 (dB), so
ior yields the transfer function shown in Figure 15.
The compression ratio of 11:1 allows a rise of only
about 4.5 dB over a 50 dB range.
Figure 15. Transfer function of feedback compressor
-100
Substituting yields
Out
which can be reduced to
Out
For output signals below the level set by the
G
Out
If we let T
-50
0
dB
-100
dB
dB
dB
= A
= In
=
= In
dB
In
dB
dB
dB
, and
dB
=10, A
+T
(1+k)
− k (Out
+ A
dB
+A
dB
dB
dB
-50
dB Out
=20, and k=10, this behav-
.
dB
− T
dB
) + A
Out
In
Page 11 of 20
dB
0
,