DRV134 Datasheet, PDF (12/30 Pages) Burr-Brown (TI) – AUDIO BALANCED LINE DRIVERS

DRV134, DRV135
SBOS094B – JANUARY 1998 – REVISED DECEMBER 2014
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Feature Description (continued)
Up to approximately 10 kHz, distortion is below the measurement limit of commonly used test equipment.
Furthermore, distortion remains relatively constant over the wide output voltage swing range (approximately 2.5
V from the positive supply and 1.5 V from the negative supply). A special output stage topology yields a design
with minimum distortion variation from lot-to-lot and unit-to-unit. Furthermore, the small and large signal transient
response curves demonstrate the stability under load of the DRV134 and DRV135.
+18V
+18V
1µF
1µF
Test Point
or
V_IN
6
+V_O
4
7
8
–In
2
7
5
DRV134
1
2
R_L
INA137
6
V_OUT
+In
1
3
5
–V_O
3
4
R₁
R₂
1µF
1µF
–18V
–18V
Figure 24. Distortion Test Circuit
8.3.2 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, V_IN is grounded and a common-mode voltage, VCM,
is applied to the output as shown in Figure 25. Ideally no differential mode signal (VOD) should appear.
However, a small mode-conversion effect causes an error signal whose magnitude is quantified by OCMR.
+18V
1µF
V_IN
4
Gnd
3
6
+V_O
7
8
300Ω⁽¹⁾
DRV134
V_OD
1
2
300Ω⁽¹⁾
5
–V_O
1µF
600Ω
V_CM = 10Vp-p
–18V
Figure 25. Output Common-Mode Rejection Test Circuit
8.3.3 Signal Balance Ratio
Signal balance ratio (SBR) measures the symmetry of the output signals under loaded conditions. To measure
SBR an input signal is applied and the outputs are summed as shown in Figure 26. V_OUT should be zero since
each output ideally is exactly equal and opposite. However, an error signal results from any imbalance in the
outputs. This error is quantified by SBR. The impedances of the DRV134 and DRV135’s output stages are
closely matched by laser trimming to minimize SBR errors. In an application, SBR also depends on the balance
of the load network.
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