Study On Low-power Ultra-wideband Transceiver For Wireless Binaural Hearing Aids

As the aging population in the worldis growing rapidly, the market demandforhearing aid devices is huge. The miniaturized hearing aid devices equipped withwireless communication and binaural signal processing will play a dominant role in thefuture. Currently, the operating power of the wireless transceiver module is in the orderof10mW, accounting for more than70%of the power consumption of a typical hearingaid device. Therefore, reducing the power consumption of the RF transceiver is the keyto reducing the overall power consumption of the hearing aid. The goal of this researchis to lower the power consumption of thewireless transceiver from10mW to1mW inorder to meet the needs of the satisfied operating hours for the small-sized,battery-powered bilateral hearing aids and other mobile terminals. This willmitigate theinconvenience caused by the frequent battery replacement, and facilitate the binauralprocessing with more complex algorithm.In this dissertaion, based on the investigation of the key technologies of binauralhearing aids and low-power wireless transceivers, we proposed two ultra-widebandtransceiver architectures to reduce the power consumption with sufficient data rate.In the first architecture, anFM-UWB transceiver with8-FSK subcarrier modulationis implemented to increase data rate. Itachieves a power consumption of5mW at750kb/s data rate. The prototype was fabricated in65nm CMOS technology. Thetransmitter uses a fast-settled PLL for subcarrier modulation, and a ring VCO withgated FLL for wideband FM modulation. The receiver utilizes a wideband low-noiseamplifier and dual BPFsto achieve robust FM demodulation with high linearity.In the second architecture, alow-power2-FSK Chirp UWB technique is proposed.It combines advantagesfrom existing IR-UWBand FM-UWB, but inhibit their inherentshortcomings. The transmitter outputs chirp pulses of10%duty cycle and500MHzbandwidth at8GHz.The receiver uses non-coherent RF demodulation based onfrequency detection and15%duty-cycled operation for the frontend to minimize thepower consumption. The backend uses oversampling method for the clock and datarecovery to achieve low-latency and low-power bit synchronization. The prototype wasfabricated in65nm CMOS process. The transceiver consumes a peak power of7.5mW,but the average power is only1mW, reaching an energy efficiency of1nJ/bit.Finally, the thesis presents a new structure of binaural hearing aids based onportable wireless terminal. It uses the Chirp-UWB as wireless solution, and it moves thedigital signal processing from the ear side to the portable terminal such asthesmartphone. This method reduces the power consumption of the hearing aids at the earside, and improves the calculation capability and flexibility of digital signal processing.Meanwhile, this structure relaxes the sensitivity requirement of the wireless receiver.