Research And Design Of Low Power ADC For Biomedical System

Recently, along with the rapid development of integrated circuit and its growing application in biomedical field, biomedical system is continuously pushing the development and implement of its microminiaturization and intellectualization, which brings improvement to the technology of disease diagnoses and treatment and thus to the human living quality. And ADC is one of the most crucial part in such a system, which converts analog biological signal to digital signal for transmission and processing. Among different ADCs, the SAR ADC (Successive Approximation Register ADC) is widely used in biomedical field due to its simple structure, low power and small area.Aiming at demands of the biomedical system, this thesis proposed a12bit200KS/s low power SAR ADC. It consists of a sample and hold switch, a charge-redistribution DAC, a time domain comparator and a successive approximation logic register. The highlight of the work is:a modified reconfigurable ladder stage time domain comparator for low power and low noise design, an integer-based split capacitor array combined with a mixed switching scheme aiming at low power and high precision, a multi-controlled clock distribution circuit to reduce power and area.The proposed SAR ADC was designed and fabricated in UMC0.18μm CMOS process under a supply voltage of0.9V. According to simulation result, the proposed SAR ADC achieved a SNDR of70dB, a power consumption of2.2μW, a FOM of4.7fJ/c-s, the core area is600μm×400μum. The result indicates that the proposed SAR ADC could meet with the microminiaturization, intellectualization and high precision requirement in biomedical system.