|Elec/CEng 499 Design Project Supervisor : Panajotis Agathoklis|
How Does it Work?
The SMA D-Class amplifier consists of both a linear, low power stage, and a digital, high power stage. At lower output power (up to 2 Watts) the linear stage amplifies the signal on its own. Current sensing resistors at the output of the linear stage send a voltage signal to a Schmidt trigger in the digital stage (D-Stage). This trigger activates the D-Stage once the output power from the linear stage reaches 2 Watts. Once the D-Stage is activated the additional power is supplied from the D-Stage rather than the linear stage.
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The linear stage amplifying low power signals ensures that the amplified audio signal is free from crossover distortion (caused when the input signal changes polarity), which is a shortcoming in most D-Class amps. The D-Stage is highly efficient, and since it provides the output power when required, the overall amplifier exhibits better power efficiency (80 -85 %) than typical linear amplifiers.
Please refer to the final report provided in the Documentation section for in depth information.