UTC571
LINEAR INTEGRATED CIRCUIT
R1
20K
G
R1
10K
C
REC
T
CF
R
D
C
RDC
R3
20K
CIN
VIN
V
OUT
R4
30K
V
REF
Figure 4. Basic Components
Figure 4 shows the hook-up for a compressor. This is essentially an expandor placed in the feedback loop of the
op amp . the ∆G cell is setup to provide AC feedback only, so a separate DC feedback loop is provide by the two
RDC and CDC. The values of RDC will determine the DC bias at the output of the amp. The output will bias to:
RDC1 + RDC2
VOUT DC = 1 +
R4
RDCTOT
VREF = (1+
)1.8V
30K
The output of the expander will bias up to:
R3
VOUT DC = 1 +
VREF
R4
20K
VREF = (1 +
)1.8V = 3.0V
30K
The output will bias to 3.0V when the internal resistor are used. External resistor may be placed in series with r3,
(which will affect the gain ), or in parallel with r4 to raise the DC bias to any desired value.
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YOUW ANG ELECTRONICS CO.LTD
UTC [ Unisonic Technologies ]
