Texas Instruments SLOU023A - Manual (Page 19)

The TPA112 MSOP Audio Power Amplifier Evaluation Module
3-5 Details
3.2.2 Module Gain
The TPA112 MSOP evaluation module has a set gain of 4 (inverting) for each
channel. However, the gain can be adjusted to a maximum of approximately
10 (inverting) by changing the value of feedback resistors (R8 and R10, Figure
3–3). Use the following equation to determine the value of R
F:
Gain + –
R
F
R
I
The TPA112 amplifier IC, like most other amplifiers, exhibits its best distortion
and noise performance at lower gain levels. In addition, higher gain levels
require a small compensation capacitor to ensure stability (see the TPA112
data sheet).
Gain versus total harmonic distortion (THD) and gain versus signal-to-noise
ratio (SNR) should be considered in each application. Both the module input
signal level and the TPA112 MSOP module gain should be adjusted to obtain
the lowest overall distortion level for a particular overall gain. A quick rule of
thumb (everything else being equal): the module input signal level should be
as high as possible without clipping or overloading the TPA112 input, and the
TPA112 gain should be kept as low as possible.