Applied To The Precision Of The Hearing Aid System Is Very Low Power Sigma-delta Modulator Design And Implementation

Further developments and great achievements have been made since the IC technology has been invented last century. It has been widely applied in industry controlling, communication, automobile, test instruments and some other portable devices. As the living standard improving, people have paid more attention to their healthy and convenience medicine. IC technology combines with traditional medicine can meet the increasing demand for medical care by providing many kinds of portable, precise and low cost medical equipment. The Medium and Long Term Development Plan of China also gives high priority to medical electronic technology. However, due to the special requirements of the medical applications, the power consumption has become a main issue which restricted the application of integrated circuits.Basing on the National 863's Plan, this paper has designed a 1-V,14-bit,8-KHz bandwidth Sigma-Delta modulator for hearing-aid applications. After introducing the research background, this paper gives the theory of Sigma-Delta ADC, and then gives the low power solutions based on system and circuit conditions; The modulator adopted an third-order single-loop feed-forward, single-bit quantization architecture to reduce system complexity; Boot-strap circuit is adopted to reduce the non-linearity of switch-on resistor of switch; In order to get low-power performance, double sampling technology is adopted, and so as two-stage class-AB Op-amps.Finally, the paper gives the test results, as well as the proposal for improvement and prospects.The modulator is realized by SMIC0.13-μm Mixed Signal CMOS process, the core chip size is about 0.5x0.5 mm2.The chip can work under 0.9-V to 1.2-V.Clocking at 1.024-MHz, the noise floor is-90-dB in an 8-KHz bandwidth,and the typical SNR is 80-dB,the SNDR is 90-dB with a power consumption of 38-μW。...