Study On Readout Circuits Applied To Quantum Dot Short-wave Infrared Detectors

With the continuous development of infrared detection and imaging technology,short-wave infrared(SWIR)has been widely used in military,civil,medical,industrial,and other fields.SWIR detectors can identify more details of an object due to their excellent resolution and dynamic range.The detection characteristics of SWIR also make it of great research prospects and value in the field of object recognition.However,when it comes to SWIR detector materials,whether based on antimonides,indium gallium arsenide,or mercury cadmium telluride,they all face challenges such as high material quality requirements,complex manufacturing processes,and high costs.These issues greatly limit the widespread adoption of SWIR sensors in the civilian market.On the other hand,SWIR detectors based on quantum dot materials have the potential to significantly reduce costs,making them highly promising in the field.Quantum dot SWIR detectors are part of the quantum dot SWIR focal plane array,with the readout circuitry being another crucial component.The close relationship between the two highlights the importance of selecting a compatible readout circuit interface when promoting the application of quantum dot SWIR detectors.Furthermore,as the scale of pixel arrays expands and the size of pixels decreases,the design and research of high-performance readout circuits hold profound significance.This study investigates the matching issue between quantum dot detectors and the input stage interface of readout circuits.Taking injection efficiency as the starting point,the input stage circuits of BDI and CTIA structures are analyzed in detail.By combining the quantum dot I-V and C-V data obtained from the research group’s tests,and using the injection efficiency formulas for both structures,the injection efficiencies of CTIA and BDI are calculated.It is found that both CTIA and BDI achieve an injection efficiency of 99%.Through further comparison,it is observed that the CTIA circuit structure demonstrates better stability in injection efficiency at different biases.Therefore,the CTIA structure is selected as the input stage interface for the quantum dot-based readout circuit in this study,effectively addressing the matching issue between the input stage interface circuit and the quantum dot SWIR detector.After determining the input stage circuit structure,the overall design of the readout circuit for quantum dot SWIR detectors is carried out.The 16x16 array ROIC(Readout Integrated Circuit)for quantum dot SWIR focal plane is designed using SMIC(Semiconductor Manufacturing International Corporation)0.18μm CMOS process.The design includes different modules such as the operational amplifier design for the input stage CTIA circuit,the CDS(Correlated Double Sampling)circuit design,the source follower design for the output stage of each pixel,the row selection shift register,the column selection shift register,the column buffer circuit,and the bus buffer circuit.In the design of the CTIA unit circuit,special attention is given to the reset switch noise and other noise issues.The correlated double sampling circuit is employed to effectively reduce the KTC(thermal noise)noise.Furthermore,sub-threshold design is used in the CTIA operational amplifier structure to reduce circuit power consumption,with a power consumption of 0.257 u W for the unit circuit.double-sampling circuits,output stages of single-pixel structures,row-column shift registers,column buffer stages,and bus buffer stages.Considering the issue of unit circuit reset switch noise and other noise,the paper uses a related double-sampling circuit to effectively reduce KTC noise when designing the CTIA unit circuit.Finally,the timing of the row and column shift registers and various control switches is designed.The operational amplifier,unit CTIA,row/column shift registers,and buffer stages are simulated.Subsequently,a 16x16 pixel readout circuit is constructed for simulation and analysis.The overall circuit can achieve the integration-then-readout mode,and its functionality is verified to be correct.This validates the overall design and lays the foundation for the subsequent chip fabrication and further research in the research group.