Texas Instruments TPA3003D2 - Manual (Page 27)

TPA3003D2
SLOS406A − FEBRUARY 2003 − REVISED MARCH 2003
27
www.ti.com
APPLICATION INFORMATION
Analyzer
20 Hz − 20 kHz
(a) Basic Class−AB
APA
Signal
Generator
Power Supply
Analyzer
20 Hz − 20 kHz
R
L
(b) Filter−Free and Traditional Class−D
Class−D APA
Signal
Generator
Power Supply
R
L
Low−Pass RC
Filter
Low−Pass RC
Filter
Figure 29. Audio Measurement Systems
The TPA3003D2 uses a modulation scheme that does not require an output filter for operation, but they do
sometimes require an RC low-pass filter when making measurements. This is because some analyzer inputs
cannot accurately process the rapidly changing square-wave output and therefore record an extremely high
level of distortion. The RC low-pass measurement filter is used to remove the modulated waveforms so the
analyzer can measure the output sine wave.