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InGenius High-CMRR
Balanced Input Line Receiver
T H A T C o r p o r a t i o n
THAT 1200, 1203, 1206
FEATURES
APPLICATIONS
·
High common-mode rejection
(typical 90 dB at 60 Hz) maintained
under real-world conditions
·
·
·
Balanced input stages
Summing amplifiers
Transformer front-end
replacements
·
·
Excellent solution for hum and
groundloop suppression
·
ADC front-ends
Transformer-like noise rejection in
an 8-pin IC, at fraction of
transformer cost and size
Description
The THAT 1200 series of InGenius balanced
Developed by Bill Whitlock of Jensen Trans-
formers, the patented InGenius input stage uses a
unique bootstrap circuit to raise its common-
mode input impedance into the megohm range,
but without the noise penalty that comes from
high-valued resistors. InGenius line receivers
maintain their high CMRR over a wide range of
source impedance imbalances — even when fed
from single-ended sources.
line receivers are designed to overcome a serious
limitation of conventional balanced input stages
— notoriously poor common mode rejection in
real world applications. While conventional input
stages may exhibit good rejection characteristics
in the lab and on paper, they perform poorly
when fed from even slightly unbalanced source
impedances — a common situation in almost any
pro sound environment.
Pin Name
Ref
DIP Pin
SO Pin
1
2
3
4
5
6
7
8
3
4
OA1
In-
R1
R2
IN-
IN+
+1
Vcc
Vee
In+
5
Rc
Rd
Ra
Rb
Vee
6
OA4
+1
OA3
CM In
Vout
Vcc
11
12
13
14
-
Vout
+
OA2
+1
R3
R4
R5
CM Out
REF
Table 1. 1200-series pin assignments
Gain
0 dB
Plastic DIP
1200P
Plastic SO
1200S
CM IN
CM OUT
-3 dB
-6 dB
1203P
1203S
Cb
1206P
1206S
Figure 1. THAT1200-series equivalent circuit diagram
Table 2. Ordering information
Protected under U.S. Patent No. 5,568,561 and other patents pending.
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InGenius is a trademark of THAT Corporation.
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
Tel: +1 (508) 478-9200; Fax: +1 (508) 478-0990; Web: www.thatcorp.com
600033 Rev 0A