Study On Amplifier And ADC Circuit Design Based On Metal Oxide TFT

Amplifier and Analog to Digital Converter(ADC)modules designed based on metal oxide thin film transistors(MOTFT)have very important role and foreseeable broad application prospect in the applications,which are related to readout circuits of large-area sensor arrays that have high requirements for circuit gain and noise.However,limited by process and materials currently,complementary(P-type)MOTFTs with matching and stable performance cannot be fabricated,which brings much challenges to the design of amplifier circuits with high-performance based on unipolar(N-type)MOTFTs.Response to the above key issues,the thesis carried out the amplifiers and ADC circuits design,based on the technology of MOTFT.The main research contents are as follows:Based on the unipolar(N-type)MOTFT,this thesis has designed an amplifier circuit with a capacitor bootstrap structure.The tape-out test data shows that the amplifier achieves a gain of 32 d B,and the equivalent input reference noise of the circuit is as low as 38.3 ?Vrms in the 1-200 Hz bandwidth.The influence of the three variables,including the number of capacitor bootstrap structures,the size of the capacitance,and the common source and cascode structures,on the gain and noise of the circuit has been analyzed.The measurement result shows that with the number of capacitor bootstrap structures increased in a small range,the gain of the circuit is significantly improved,and the equivalent input reference noise is reduced;and the change of capacitance can affect the gain and noise of the circuit,but the impact is relatively weak;In addition,the use of cascode structure has better performance in terms of gain and noise than the common source structure.A 3-bit parallel(Flash structure)ADC based on MOTFT has been designed.The simulation results show that the maximum differential nonlinearity error(DNL)and integral nonlinearity error(INL)realized by this circuit at a sampling rate of 4 Ks/s are-0.37624 and0.3196 LSB,respectively.And the delay time achieved by the ADC circuit is about 121 ?s.The comparator module in the ADC circuit has been optimized and fabricated,and the measurement result shows that under the condition of 10 V supply voltage,the best resolution achieved by the comparator is about 500 m V with the 0.9-9.3 V of output voltage swing.Moreover,the power consumption of the comparator is output swing is 83.5 ?W as the measurement result shows.The designed amplifier circuits based on Mo TFT in this research achieves good performance of high gain and low noise,which provides a reference for the study of noise analysis of Mo TFT amplifier.The ADC circuit designed with flash structure in this thesis verifies the feasibility of this kind of Mo TFT material in ADC circuit design,and fills the gap in this field in China,which has reference significance for the subsequent ADC circuit design based on Mo TFTs.