The book "Digital Pulse Width Modulator" by Huiyun Li offers a comprehensive analysis and description of the design of a micropower digital pulse width modulator (PWM) for Class D amplifiers in hearing aids. It addresses innovative approaches such as the delta-compensation sampling process and a novel pulse generator, both aimed at improving the performance and efficiency of hearing aids. The PWM is characterized by simplified arithmetic calculations while maintaining a low total harmonic distortion (THD). The analytical derivation of the double Fourier series is also discussed to support the modulator's performance. The book is particularly valuable for professionals and students involved in the development and implementation of digital circuits in audio technology.