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We describe the design of a micropower digital
pulsewidth modulator (PWM) for a hearing instrument
Class D amplifier. The PWM embodies a novel delta-
compensation sampling process and a novel pulse
generator.The delta-compensation sampling process is
sampled at the same low rate as reported algorithmic
sampling processes and it features a similar low
total harmonic distortion (THD). Its arithmetic
computation is however, substantially simplified.
We analytically derive the double Fourier series
expression and show that the THD is low.The pulse
generator is based on a hybrid 9-b counter 3-b
tapped-delay-line. We investigate the compromise
between the different design parameters that affect
its power dissipation and THD. The complete proposed
PWM features a simple circuit implementation,
micropower low voltage operation, low sampling rate
and low harmonic distortion, thereby rendering it
suitable for a practical digital hearing instrument.
About the author
Huiyun Lireceived the Ph.D degree from University of Cambridgein 2006. She is now with Shenzhen Institute of AdvancedTechnology, Chinese Academy of Sciences, China.Gwee Bah Hwee received the MEng and PhD degrees from NanyangTechnological University, Singapore in 1992 and 1998. He is withNanyang Technological University since 1999.
