How is the class d Amplifier composed?
- The amplifier is composed of a comparator linked to two MOSFET transistors which work as switches. The comparator has two entries, one is a triangular signal and the other one is an audio signal (see Figure 1 mentioned below).
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- Both components work as switches (not taking into account if the source is positive or negative) sometimes named saturated switch. When the output of the component is saturated, it doesn’t lose energy because in this state either voltage or current is equal to zero. The heating of the system is only during the transitional stage of the switch; however this heat can be reduced.
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The audio signal is compared to a high frequency triangle signal. This gives an intermediate square signal, width modulated (PWM) at the rate of the audio signal.
The power MOS transistor (complementary or not) working in "ON / OFF".
An output filter, placed between the floor and the load MOS (Speaker), can restore the LF component (audio).