Datasheet

IN OUT
BW
+
+
LME49600LME49710
-
+
10
:
V
IN
1 k:
0.1PF
V
CC
V
EE
0.1PF
V
EE
10 PF
V
CC
R
L
10 PF
V
-
V
+
R1
R2
IN OUT
BW
+
+
LME49600LME49710
-
+
V
IN
0.1PF
0.1PF
10 PF
R
L
10 PF
V
CC
V
CC
V
EE
V
EE
R
FB
V
+
V
-
R
IN
LME49600
www.ti.com SNAS422E –JANUARY 2008–REVISED APRIL 2013
TYPICAL APPLICATION DIAGRAM
Figure 26. High Performance, High Fidelity LME49600 Audio Buffer Application
DISTORTION MEASUREMENTS
The vanishingly low residual distortion produced by LME49710/LME49600 is below the capabilities of all
commercially available equipment. This makes distortion measurements just slightly more difficult than simply
connecting a distortion meter to the amplifier’s inputs and outputs. The solution, however, is quite simple: an
additional resistor. Adding this resistor extends the resolution of the distortion measurement equipment.
The LME49710/LME49600’s low residual distortion is an input referred internal error. As shown in Figure 27,
adding the 10Ω resistor connected between the amplifier’s inverting and non-inverting inputs changes the
amplifier’s noise gain. The result is that the error signal (distortion) is amplified by a factor of 101. Although the
amplifier’s closed-loop gain is unaltered, the feedback available to correct distortion errors is reduced by 101,
which means that measurement resolution increases by 101. To ensure minimum effects on distortion
measurements, keep the value of R1 low as shown in Figure 27.
This technique is verified by duplicating the measurements with high closed loop gain and/or making the
measurements at high frequencies. Doing so produces distortion components that are within the measurement
equipment’s capabilities. This data sheet’s THD+N and IMD values were generated using the above described
circuit connected to an Audio Precision System Two Cascade.
Figure 27. THD+N Distortion Test Circuit
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