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
·
·
·
·
InGenius
â
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.
Pin Name
DIP Pin
1
2
3
4
5
6
7
8
SO Pin
3
4
5
6
11
12
13
14
OA1
IN-
Ra
+1
Rc
Ref
R1
R2
Vcc
Vee
Vout
In-
In+
Vee
CM In
Vout
Vcc
OA4
+1
OA3
-
+
R4
R5
Rb
IN+
OA2 Rd
+1
R3
CM Out
REF
Table 1. 1200-series pin assignments
Gain
0 dB
Plastic DIP
1200P
1203P
1206P
Plastic SO
1200S
1203S
1206S
CM IN
CM OUT
Cb
-3 dB
-6 dB
Figure 1. THAT1200-series equivalent circuit diagram
Table 2. Ordering information
Protected under U.S. Patent No. 5,568,561 and other patents pending.
InGenius
â
is a trademark of THAT Corporation.
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
600033 Rev 0A
Tel: +1 (508) 478-9200; Fax: +1 (508) 478-0990; Web: www.thatcorp.com
Page 2
InGenius Balanced Line Receiver
Preliminary Information
SPECIFICATIONS
1
Absolute Maximum Ratings (T
A
= 25°C)
Positive Supply Voltage (V
CC
)
Negative Supply Voltage (V
EE
)
Positive Input Voltage (V
IN+
)
Negative Input Voltage (V
IN-
)
Output Short-Circuit Duration (t
SH
)
+18 V
-18 V
+18 V
-18 V
Continuous
Power Dissipation (P
D
) (T
A
= 75°C)
Operating Temperature Range (T
OP
)
Storage Temperature Range (T
ST
)
Junction Temperature (T
J
)
Lead Temperature (Soldering 60 seconds)
TBD mW
0 to +70°C
-40 to +125°C
150°C
TBD °C
Recommended Operating Conditions
Parameter
Positive Supply Voltage
Negative Supply Voltage
Symbol
V
CC
V
EE
Conditions
Min
+3
-3
Typ
Max
+18
-18
Units
V
V
Electrical Characteristics
Parameter
Supply Current
Input Bias Current
Symbol
I
CC
I
B
Conditions
No signal
No signal; Either input
connected to GND
No signal
No signal
2
Min
—
—
Typ
4.7
700
Max
8.0
1,400
Units
mA
nA
Input Offset Current
Input Offset Voltage
Input Voltage Range
I
B-OFF
V
OFF
V
IN-CM
V
IN-DIFF
—
—
—
—
±13.0
21.5
24.5
24.5
48.0
with bootstrap
10.0
3.2
no bootstrap
36.0
36.0
±140
10
—
—
—
—
nA
mV
V
dBu
dBu
dBu
kW
MW
MW
kW
kW
Common mode
±12.5
Differential (equal and opposite swing)
THAT 1200
21.0
THAT 1203
24.0
THAT 1206
24.0
Differential
Common mode
60 Hz
20 kHz
60 Hz
20 kHz
Input Impedance
Z
IN-DIFF
Z
IN-CM
1. All specifications are subject to change without notice.
2. Unless otherwise noted, T
A
=25°C, V
CC
= +15V, V
EE
= -15V
3. 0 dBu = 0.775Vrms.
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
Preliminary Information
Page 3
Electrical Characteristics (Cont’d)
Parameter
Common Mode Rejection
Symbol
CMR
1
Conditions
Min
Typ
90
90
85
Max
—
—
—
Units
dB
dB
dB
Matched source impedances; V
CM
= ±10V
DC
70
60 Hz
70
20 kHz
—
Common Mode Rejection
CMR
2
600W unmatched source impedances
4
; V
CM
= ±10V
60 Hz
—
70
20 kHz
—
65
At 60 Hz, with V
CC
= -V
EE
THAT1200
THAT1203
THAT1206
At CM output, at 60 Hz
—
—
dB
dB
Power Supply Rejection
5
PSR
—
—
—
—
82
80
80
63
—
—
—
—
dB
dB
dB
dB
Power Supply Rejection
6
PSR
CM
THD
Total Harmonic Distortion
V
IN-DIFF
= 10 dBV; BW = 20 kHz; f = 1 kHz
RL =2 kW
—
BW = 20 kHz
THAT1200
THAT1203
THAT1206
At CM output
R
L
= 10 kW; C
L
= 300 pF
With CM input signal
R
Lcm
= 10 kW; C
Lcm
= 50 pF
R
L
= 10 kW; C
L
= 10 pF
THAT1200
THAT1203
THAT1206
R
L
= 2 kW; C
L
= 300 pF
THAT1200
THAT1203
THAT1206
At CM output; R
Lcm
= 10 kW
C
Lcm
= 10 pF
C
Lcm
= 50 pF
f = 1 kHz; R
L
= 2 kW
At max differential input
THAT1200
THAT1203
THAT1206
0.0005
—
%
Output Noise
e
n(OUT)
—
—
—
—
7*
12.5*
-106
-105
-107
-106
12
21
—
—
—
—
—
—
dBu
dBu
dBu
dBu
V/µs
V/µs
Output Noise
Slew Rate
Slew Rate
e
nCM(OUT)
SR
SR
CM
Small Signal Bandwidth
BW
-3dB
—
—
—
—
—
—
22
27
34
17
18
20
—
—
—
—
—
—
MHz
MHz
MHz
MHz
MHz
MHz
Small Signal Bandwidth
BW
CM-3dB
—
—
—
20
18
0
—
—
±0.05
MHz
MHz
dB
Output Gain Error
Output Voltage Swing
G
ER(OUT)
V
O
21
21
18
21.5
21.5
18.5
—
—
—
dBu
dBu
dBu
4. See test circuit in Figure 2.
5. Defined with respect to the differential gain.
6. Defined with respect to the common mode gain between any input and common mode output.
* Guaranteed by design
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
Tel: +1 (508) 478-9200; Fax: +1 (508) 478-0990; Web: www.thatcorp.com
Page 4
InGenius Balanced Line Receiver
Preliminary Information
Electrical Characteristics (Cont’d)
Parameter
Output Short Circuit Current
Symbol
I
SC
I
CMSC
R
Lmin
R
LCMmin
C
Lmax
C
LCMmax
Conditions
R
L
= R
Lcm
= 0
W
At CM output
Min
—
—
2
10
—
—
Typ
±25
±10
—
—
—
—
Max
—
—
—
—
300
50
Units
mA
mA
kW
kW
pF
pF
Minimum Resistive Load
At CM output
Maximum Capacitive Load
At CM output
Cb
100u
R3
600R
In+
Vcc
2
R5
C1
56p
C4
100R
CM Out
Gnd
In-
R1
200k
R2
200k
8
In-
7
100n
CMout
Vcc
5
Out
CMin
Ref
6
Vee
3
1
In+
4
U1
R6
100R
R4
2k
C2
300p
Main Out
Gnd
C3
100n
Ext. DC Source
Gnd
Vee
THAT120x
Figure 2. THAT1200-series test circuit
Applications
RFI Protection
Figure 3 shows the THAT 1200 configured with
robust RFI input protection. In applications where
RFI rejection is of less concern, the circuit shown Fig-
ure 4 provides a less aggressive approach.
the low end of the audio spectrum. Its voltage rating
is dependent on the topology of the surrounding cir-
cuitry, as described in the following paragraphs.
AC signals presented to the input stage cause the
two ends of capacitor Cb to swing in tandem so that
virtually no voltage appears across the capacitor.
Consequently, capacitors with small DC working volt-
ages may be used when the previous stage is AC cou-
pled to the input of the THAT 1200.
Bootstrap coupling capacitor
Referring to Figure 3, electrolytic capacitor Cb
provides the feedback path for the boostrap circuit.
The capacitor value is chosen to be high enough to
present a sufficiently small impedance to signals at
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
Preliminary Information
Page 5
Vcc
2 1
3
5 423 1
J1
XLR-F
D3
C2
470pF
C3
470pF
D1
12V
R1
100R
D4
Cb
220uF
+
(see text)
2
IN-
8
Vcc
R3
4k7
C4
100pF
D5
D2
12V
D6
R2
100R
7
U1
CM
OUT VCC
5 CM
OUT
IN
VEE
REF
3 IN+
4
1
Vee
6
OUT
optional RFI protection
Vee
Figure 3. THAT1200P typical application circuit
If, however, there is the possibility of a DC voltage
appearing across the inputs of the line receiver, a
portion of that voltage will appear directly across the
terminals of capacitor Cb. In that case, choose the
capacitor’s voltage rating so that it is capable of han-
dling the expected level of DC voltage. If the polarity
of the DC voltage is unknown, or may swing to either
polarity, the use of a non-polarized electolytic is
highly recommended.
Vcc
2
3
1
Cb
D1
12V
J1
XLR-F
D3
+
Vcc
220uF
D4
2
54231
C1
C2
100pF NPO
100pF NPO
D5
D2
12V
Vee
D6
8
IN-
7
U1
CM
OUT VCC
5 CM
OUT
IN
VEE
REF
3 IN+
4
1
Vee
6
OUT
Figure 4. THAT1200P showing simplified RFI protection scheme
THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA
Tel: +1 (508) 478-9200; Fax: +1 (508) 478-0990; Web: www.thatcorp.com
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