THAT Corporation; 45 Sumner Street; Milford, Massachusetts 01757-1656; USA

Tel: +1 (508) 478-9200; Fax: +1 (508) 478-0990; Web: www.thatcorp.com

THAT 1200, 1203, 1206

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.

T H A T

C o r p o r a t i o n

InGenius

High-CMRR

Balanced Input Line Receiver

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

APPLICATIONS

Balanced input stages

Summing amplifiers

Transformer front-end
replacements

ADC front-ends

IN-

IN+

REF

CM OUT

Vcc

Vee

Vout

CM IN

OA1

OA2

OA3

OA4

Figure 1. THAT1200-series equivalent circuit diagram

Pin Name

DIP Pin

SO Pin

Ref

In-

In+

Vee

CM In

Vout

Vcc

CM Out

Table 1. 1200-series pin assignments

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

Page 2

InGenius Balanced Line Receiver

Preliminary Information

Absolute Maximum Ratings (T

= 25°C)

Positive Supply Voltage (V

)

+18 V

Power Dissipation (P

) (T

= 75°C)

TBD mW

Negative Supply Voltage (V

)

-18 V

Operating Temperature Range (T

)

0 to +70°C

Positive Input Voltage (V

IN+

)

+18 V

Storage Temperature Range (T

)

-40 to +125°C

Negative Input Voltage (V

IN-

)

-18 V

Junction Temperature (T

)

150°C

Output Short-Circuit Duration (t

)

Continuous

Lead Temperature (Soldering 60 seconds)

TBD °C

Electrical Characteristics

Parameter

Symbol

Conditions

Min

Typ

Max

Units

Supply Current

No signal

4.7

8.0

Input Bias Current

No signal; Either input

700

1,400

connected to GND

Input Offset Current

B-OFF

No signal

±140

Input Offset Voltage

OFF

No signal

Input Voltage Range

IN-CM

Common mode

±12.5

±13.0

IN-DIFF

Differential (equal and opposite swing)

THAT 1200

21.0

21.5

dBu

THAT 1203

24.0

24.5

dBu

THAT 1206

24.0

24.5

dBu

Input Impedance

IN-DIFF

Differential

48.0

IN-CM

Common mode

with bootstrap

60 Hz

10.0

20 kHz

3.2

no bootstrap

60 Hz

36.0

20 kHz

36.0

Recommended Operating Conditions

Parameter

Symbol

Conditions

Min

Typ

Max

Units

Positive Supply Voltage

+18

Negative Supply Voltage

-3

-18

SPECIFICATIONS

1. All specifications are subject to change without notice.

2. Unless otherwise noted, T

=25°C, V

= +15V, V

= -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

Page 3

Preliminary Information

Electrical Characteristics (Cont'd)

Parameter

Symbol

Conditions

Min

Typ

Max

Units

Common Mode Rejection

CMR

Matched source impedances; V

= ±10V

60 Hz

20 kHz

Common Mode Rejection

CMR

600

W unmatched source impedances

; V

= ±10V

60 Hz

20 kHz

Power Supply Rejection

PSR

At 60 Hz, with V

= -V

THAT1200

THAT1203

THAT1206

Power Supply Rejection

PSR

At CM output, at 60 Hz

Total Harmonic Distortion

THD

IN-DIFF

= 10 dBV; BW = 20 kHz; f = 1 kHz

RL =2 k

0.0005

Output Noise

n(OUT)

BW = 20 kHz

THAT1200

-106

dBu

THAT1203

-105

dBu

THAT1206

-107

dBu

Output Noise

nCM(OUT)

At CM output

-106

dBu

Slew Rate

= 10 k

W; C

= 300 pF

V/µs

Slew Rate

With CM input signal

12.5*

V/µs

Lcm

= 10 k

W; C

Lcm

= 50 pF

Small Signal Bandwidth

-3dB

= 10 k

W; C

= 10 pF

THAT1200

MHz

THAT1203

MHz

THAT1206

MHz

= 2 k

W; C

= 300 pF

THAT1200

MHz

THAT1203

MHz

THAT1206

MHz

Small Signal Bandwidth

CM-3dB

At CM output; R

Lcm

= 10 k

Lcm

= 10 pF

MHz

Lcm

= 50 pF

MHz

Output Gain Error

ER(OUT)

f = 1 kHz; R

= 2 k

±0.05

Output Voltage Swing

At max differential input

THAT1200

21.5

dBu

THAT1203

21.5

dBu

THAT1206

18.5

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

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.

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

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.

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

Symbol

Conditions

Min

Typ

Max

Units

Output Short Circuit Current

= R

Lcm

= 0

±25

CMSC

At CM output

±10

Minimum Resistive Load

Lmin

LCMmin

At CM output

Maximum Capacitive Load

Lmax

300

LCMmax

At CM output

In-

In+

CMin

Out

THAT120x

100u

56p

C2
300p

100n

200k

R2
200k

600R

R4
2k

100R

Vcc

Vee

In-

In+

Ext. DC Source

CM Out

Main Out

Gnd

CMout

Vcc

Ref

Vee

Figure 2. THAT1200-series test 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.

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

Page 5

Preliminary Information

IN-

IN+

OUT

CM
IN

OUT

REF

VCC

VEE

220uF

5 4

3 1

J1
XLR-F

Vcc

Vee

OUT

100pF NPO

Vcc

Vee

12V

Figure 4. THAT1200P showing simplified RFI protection scheme

IN-

IN+

OUT

REF

VCC

VEE

4k7

220uF

470pF

100pF

5 4 3 1

J1
XLR-F

Vcc

Vee

OUT

100R

(see text)

optional RFI protection

Vcc

Vee

12V

Figure 3. THAT1200P typical application circuit

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