V

3

5

6

1

3

INA2134

V

OUT = V3 – V2

2

R

3

25kW

R

4

25kW

R

1

25kW

R

2

25kW

V

2

–In

+In

1µF

V–

4

1µF

V+

7

INA2134-EP

www.ti.com

SBOS595C – MARCH 2012 – REVISED MARCH 2012

APPLICATION INFORMATION

Basic Connection

Figure 2 shows the basic connections required for operation of the INA2134. Decoupling capacitors are strongly

recommended in applications with noisy or high impedance power supplies. The capacitors should be placed

close to the device pins as shown in Figure 2. All circuitry is completely independent in the dual version assuring

lowest crosstalk and normal behavior when one amplifier is overdriven or short-circuited.

As shown in Figure 2, the differential input signal is connected to pins 2 and 3. The source impedances

connected to the inputs must be nearly equal to assure good common mode rejection. A 10-

Ω mismatch in

source impedance will degrade the common-mode rejection of a typical device to approximately 74 dB. If the

source has a known impedance mismatch, an additional resistor in series with the opposite input can be used to

preserve good common-mode rejection.

Do not interchange pins 1 and 3 or pins 2 and 5, even though nominal resistor values are equal. These resistors

are laser trimmed for precise resistor ratios to achieve accurate gain and highest CMR. Interchanging these pins

would not provide specified performance.

Figure 2. Precision Difference Amplifier (Basic Power Supply and Signal Connections)

Audio Performance

The INA2134 was designed for enhanced ac performance. Very low distortion, low noise, and wide bandwidth

provide superior performance in high quality audio applications. Laser-trimmed matched resistors provide

optimum common-mode rejection (typically 90 dB), especially when compared to circuits implemented with an

operational amplifier and discrete precision resistors. In addition, high slew rate (14 V/µs) and fast settling time

(3 ms to 0.01%) ensure good dynamic performance.

The INA2134 has excellent distortion characteristics. THD+Noise is below 0.002% throughout the audio

frequency range. Up to approximately 10-kHz distortion is below the measurement limit of commonly used test

equipment. Furthermore, distortion remains relatively flat over its wide output voltage swing range (approximately

1.7 V from either supply).

Offset Voltage Trim

The INA2134 is laser trimmed for low offset voltage and drift. Most applications require no external offset

adjustment. Figure 3 shows an optional circuit for trimming the output offset voltage. The output is referred to the

output reference terminal (pin 1), which is normally grounded. A voltage applied to the Ref terminal will be

summed with the output signal. This can be used to null offset voltage as shown in Figure 3. The source

impedance of a signal applied to the Ref terminal should be less than 10

Ω to maintain good common-mode

rejection.

Copyright © 2012, Texas Instruments Incorporated

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