9

®

DRV134, 135

Excellent internal design and layout techniques provide low

signal distortion, high output level (+27dBu), and a low

noise floor (–98dBu). Laser trimming of thin film resistors

assures excellent output common-mode rejection (OCMR)

and signal balance ratio (SBR). In addition, low dc voltage

offset reduces errors and minimizes load currents.

For best system performance, it is recommended that a high

input-impedance difference amplifier be used as the re-

ceiver. Used with the INA134 (G = 0dB) or the INA137 (G

=

±6dB) differential line receivers, the DRV134 forms a

complete solution for driving and receiving audio signals,

replacing input and output coupling transformers commonly

used in professional audio systems (Figure 2). When used

with the INA137 (G = –6dB) overall system gain is unity.

AUDIO PERFORMANCE

The DRV134 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 output

common-mode rejection (typically 68dB), especially when

compared to circuits implemented with op amps and discrete

precision resistors. In addition, high slew rate (15V/

µs) and

fast settling time (2.5

µs to 0.01%) ensure excellent dynamic

response.

The DRV134 has excellent distortion characteristics. As

shown in the distortion data provided in the typical perfor-

mance curves, THD+Noise is below 0.003% throughout the

audio frequency range under various output conditions. Both

differential and single-ended modes of operation are shown.

In addition, the optional 10

µF blocking capacitors used to

mance. Measurements were taken with an Audio Precision

System One (with the internal 80kHz noise filter) using the

THD test circuit shown in Figure 3.

Up to approximately 10kHz, distortion is below the mea-

surement limit of commonly used test equipment. Further-

more, distortion remains relatively constant over the wide

output voltage swing range (approximately 2.5V from the

positive supply and 1.5V from the negative supply). A

special output stage topology yields a design with minimum

distortion variation from lot-to-lot and unit-to-unit. Further-

more, the small and large signal transient response curves

demonstrate the DRV134’s stability under load.

OUTPUT COMMON-MODE REJECTION

Output common-mode rejection (OCMR) is defined as the

change in differential output voltage due to a change in

output common-mode voltage. When measuring OCMR,

applied to the output as shown in Figure 4. Ideally no

small mode-conversion effect causes an error signal whose

magnitude is quantified by OCMR.

FIGURE 3. Distortion Test Circuit.

FIGURE 4. Output Common-Mode Rejection Test Circuit.

(

)

V

OD

V

CM

600

Ω

V

300

300

OCMR = –20 Log

at f = 1kHz, V

NOTE: (1) Matched to 0.1%.

V

IN

Gnd

+V

O

V

OD

–V

O

DRV134

1

µF

+18V

6

8

1

7

2

1

µF

–18V

5

4

3

R

1

R

2

R

L

V

OUT

INA137

1

µF

V

IN

+V

O

–In

+In

–V

O

+18V

7

2

3

6

1

5

1

µF

–18V

4

DRV134

1

µF

+18V

6

8

1

7

2

1

µF

–18V

NOTE: Cable loads, where indicated, are Belden 9452 cable.

5

4

3

Test Point

or