that1240 THAT Corporation, that1240 Datasheet - Page 7
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that1240
Manufacturer Part Number
that1240
Description
Balanced Line Receiver Ics
Manufacturer
THAT Corporation
Datasheet
1.THAT1240.pdf
(8 pages)
Document 600035 Rev 04
conversion (degrading CMRR) when there are even
slight differences in gain between the VCAs. A better
approach is to convert the signal to single-ended,
alter the gain, and then convert back to balanced.
receiver to do the balanced-to-single-ended conver-
sion. The VCA section also has a static gain of -3 dB
due to the ratio of R
In Figure 13 we use a THAT 1243 -3 dB line
Figure 10. Precision two-input summing circuit
Input 2
Input 1
2
3
In-
In+
+24 dBu In
In Lo
In Hi
9k
9k
2
to R
7
4
V
V
Tel: +1 508 478 9200; Fax: +1 508 478 0990; Web: www.thatcorp.com
CC
EE
THAT Corporation; 45 Sumner Street; Milford, MA 01757-1656; USA
3
. This circuit can accept
9k
9k
Sense
U1
1240
Vout
Ref
3
2
Figure 12. Circuit for audio ADCs with balanced inputs
Figure 13. Automated gain control of a balanced signal
In-
In+
5
6
1
Sense
1
Ref
Copyright © 2008, THAT Corporation
Output
5
Vout
THAT
1246
U2
2
3
6
In-
In+
Sense
Ref
1
Page 7 of 8
5
Vout
THAT
1246
U1
1
U3A
4570
+24 dBu
6
+24 dBu, since the THAT 1243 output stage is
capable of accepting 21 dBu without distortion.
Reducing R
VCA output noise. This arrangement results in 3 dB
greater dynamic range compared to the case where a
-6 dB line receiver and a VCA with zero dB static gain
are used. After the VCA, the signal is restored to 24
dBu by the THAT 1606.
3
2
2k10
2k10
R19
1/2 Vref of ADC
In+
R8
In-
R1
Rg
C4
6n8
Figure 11. Instrumentation amplifier
3
to 14 kΩ results in a 3 dB reduction in
6
5
3
2
4k99
4k99
R2
R3
U2A
OP-270B
U2B
OP-270B
R9
249R
7
1
AIN+ to ADC
AIN- to ADC
Zero dBu Out
100n
2
3
Balanced Line Receiver ICs
C1
100n
C2
In-
In+
V
V
V
CC
CC
V
EE
7
EE
4
Sens
Ref
THAT 1240 Series
1
5
Out
THAT1240
U1
6
Out