T H AT Corporation
FEATURES
· High common-mode rejection
(typical 90 dB at 60 Hz) maintained
under real-world conditions
· Excellent solution for hum and
groundloop suppression
· Transformer-like noise rejection in
an 8-pin IC, at fraction of
transformer cost and size
InGeniusâ High-CMRR
Balanced Input Line Receiver
THAT 1200, 1203, 1206
APPLICATIONS
· Balanced input stages
· Summing amplifiers
· Transformer front-end
replacements
· ADC front-ends
Description
The THAT 1200 series of InGenius balanced
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.
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.
IN-
Ra
Rb
IN+
OA1
+1
Rc
OA2 Rd
+1
R1
OA4
+1
R3
R2
OA3
-
+
R4
R5
Vcc
Vee
Vout
REF
Pin Name
Ref
In-
In+
Vee
CM In
Vout
Vcc
CM Out
DIP Pin
1
2
3
4
5
6
7
8
SO Pin
3
4
5
6
11
12
13
14
Table 1. 1200-series pin assignments
CM IN
CM OUT
Cb
Figure 1. THAT1200-series equivalent circuit diagram
Gain
Plastic DIP Plastic SO
0 dB
1200P
1200S
-3 dB
1203P
1203S
-6 dB
1206P
1206S
Table 2. Ordering information
Protected under U.S. Patent No. 5,568,561 and other patents pending.
InGeniusâ is a trademark of THAT Corporation.
600033 Rev 0A
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
Tel: +1 (508) 478-9200; Fax: +1 (508) 478-0990; Web: www.thatcorp.com
