How does a Class D amplifier work and what are its advantages?

Class D amplifiers use pulse-width modulation (PWM) to switch output transistors fully ON or OFF, theoretically achieving 100% efficiency (practically 90-95%). The audio signal modulates the duty cycle of a high-frequency carrier (typically 400kHz-1MHz). A low-pass filter reconstructs the analog signal at the output. Advantages include high efficiency (minimal heat, smaller heatsinks), compact size, and lower power supply requirements. Challenges include EMI, output filter design, and maintaining THD comparable to linear amplifiers.