基于数字放大器的电容数字转换器OACSTPCD

The traditional switched-capacitor(SC)capacitance-to-digital converter(CDC)based on SAR ADC uses high-voltage power supply to increase output swing in order to achieve a high capacitance detection range.However,to maintain noise performance,they re-quire high current drive,significantly increasing system power consumption.To address the above issues,this article proposes a capaci-tance-to-digital converter based on a digital amplifier,which uses the CDAC array as the analog output to bear high voltage.Only the CD AC array and sensing capacitors are driven by high voltage(5 V),while the rest is still powered by low voltage(1 V),allowing the CDC to achieve high dynamic range and sensitivity while maintaining low power consumption and low noise.In addition,for the optimi-zation of noise,this work achieves first-order noise shaping for SAR ADC by adding an integral loop in the digital amplifier,reducing the quantization noise of the system and improving the effective number of bits for CDC.On the other hand,by introducing active noise can-cellation(ANC)technology,the system's aliasing noise is reduced and the signal-to-noise ratio is improved.