18.1 A 1V 3mA 2.4GHz wireless digital audio communication SoC for hearing-aid applications in 0.18μm CMOS

Hearing aids are complex integrated and highly miniaturised systems based on digital signal processor and wireless communication chips. There is a growing need for wireless connectivity between hearing aids and external devices such as cellular phone, PC, sound players (TV, radio, car navigation), remote microphones or even alarm systems. Assistive listening devices based on miniaturized FM receivers [1] operating around 200MHz have been in use for more than 15 years by hearing impaired people. A wireless microphone worn by the speaker (e.g. the teacher in a classroom) captures the speaker´s voice clearly and transmits it directly into the hearing aids. Assistive listening devices are essential for increasing speech understanding in noisy situations such as a restaurant, a classroom or a professional meeting. The evolution of FM systems for hearing impaired people has reached its limits and there is a need for a better system, eliminating frequency management by the user, providing worldwide operation, privacy of communication and better audio quality. This paper describes a digital wireless radio SoC for hearing aid applications, operating in the worldwide available 2.4GHz ISM band.