TPA3003D2

SLOS406A − FEBRUARY 2003 − REVISED MARCH 2003

27

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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.