Datasheet

C
C2
R
B1
R
B2
C
F
C
C1
V
+
A
V
= 1 +
R
2
R
1
+
-
V
IN
+
-
R
1
1 k:
R
2
10 k:
V
OUT
+
-
= 11
C
C1
+
V
OUT
+
-
-
C
F
V
IN
+
-
R
B1
V
+
R
B2
C
C2
R
2
R
1
A
V
=
-
= -10
R
2
10 k:
R
1
1 k:
LM6211
SNOSAH2C –FEBRUARY 2006–REVISED MARCH 2013 www.ti.com
AUDIO PREAMPLIFIER
With low input referred voltage noise, low supply voltage and low supply current, and low harmonic distortion, the
LM6211 is ideal for audio applications. Its wide unity gain bandwidth allows it to provide large gain over a wide
frequency range and it can be used to design a preamplifier to drive a load of as low as 600Ω with less than
0.001% distortion. Two amplifier circuits are shown in Figure 44 and Figure 45. Figure 44 is an inverting
amplifier, with a 10 kΩ feedback resistor, R
2
, and a 1 kΩ input resistor, R
1
, and hence provides a gain of −10.
Figure 45 is a non-inverting amplifier, using the same values for R
1
and R
2
, and provides a gain of 11. In either of
these circuits, the coupling capacitor C
C1
decides the lower frequency at which the circuit starts providing gain,
while the feedback capacitor C
F
decides the frequency at which the gain starts dropping off. Figure 46 shows the
frequency response of the circuit in Figure 44 with different values of C
F
.
Figure 44. Inverting Audio Amplifier
Figure 45. Non-Inverting Audio Preamplifier
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