Design And Realization Of High Accuracy Voltage Measurement Circuit Based On ADC

Analog-digital converter has been critical device in the field of digital measurement. Accroding to different structure, it has been divided into SAR type, Sigmadelt type, double slope or multi-slope integration type and VFC type. This thesis researched a new integration oversampling ADC which has higher sampling frequency than special ADC, and higher precision than common integrated ADC. For proving correctness of the integration oversampling theory and verifying applicability of this type ADC, this thesis has designed and realized a specialized voltage measure or conver circuit based on integrated ADC. The main content of the thesis includes the following:1. The circuit structure and process of integration oversampling ADC would be analyzed. The classical quantizing noise equation and oversampling theory would be made an improvement. Than this thesis deduce a new SNR equation for integration oversampling ADC would be deduced, and propse critical condition.2. Self-calibration of integration oversampling ADC would be analyzed. This thesis research the self-calibration about Iterative terms errors, charge injection errors and integrated ADC linearity error. Discharing quantitatively and measuring directly are two way of making compensation for discharing time error would be porposed.3. The ADC test theory which is histogram test and FFT test would be researched. First an ADC mathematical model with DC error would be moded in Matlab. Then algorithm of histogram test and FFT test would be analyzed. The last, simulation and verification for histogram test and FFT test would be accomplish in Matlab.4. For proving and verifying the theory of integration oversampling, A 14 bit integrated ADC would be oversampled 16 times by integration oversampling way. This thesis proposed that an 18 bit integration oversampling ADC which has bipolar input voltage range of-2 ~ +2 V, sampling frequency of 10 kHz.5. The 18 bit ADC would be test. With using histogram test, the result indicate that a maximum DLE less than 0.8 LSB, and a maximum ILE less than 4 LSB. With using FFT test, the result indicated that 91.87 dB SINAD, 92.03 dB SNR,-110.93 dB THD, 107.03 dB SFDR and 14.96 ENOB.