一个128×128 CMOS快照模式焦平面读出电路设计

A 128×128 CMOS Snapshot Readout Circuit Design for Focal Plane Array

本文介绍了一个工作于快照模式的CMOS焦平面读出电路新结构———DCA(Direct injectionChargeAmpli fier)结构 .该结构像素电路仅用 4个MOS管 ,采用特殊的版图设计并用PMOS管做复位管 ,既可保证像素内存储电容足够大 ,又可避免复位电压的阈值损失 ,从而提高了读出电路的电荷处理能力 .由于像素电路非常简单 ,且该结构能有效消除列线寄生电容Cbus的影响 ,因此该结构非常适用于小像素、大规模的焦平面读出电路 .采用DCA结构和 1 2 μm双硅双铝 (DPDM Double PolyDouble Metal)标准CMOS工艺设计了一个 12 8× 12 8规模焦平面读出电路试验芯片 ,其像素尺寸为 5 0× 5 0 μm2 ,电荷处理能力达 11 2pC .本文详细介绍了该读出电路的体系结构、像素电路、探测器模型和工作时序 ,并给出了精确的HSPICE仿真结果和试验芯片测试结果 .

A novel CMOS snapshot readout structure called DCA (Direct-injection Charge Amplifier) for focal-plane array (FPA) is presented in this paper.The pixel circuit includes only four MOS transistors.Using PMOSFET as the reset transistor with careful layout design,this pixel circuit not only can keep the in-pixel-capacitance large enough,but also can avoid the threshold voltage loss during the reset for the integration node.Thereby,charge capacity of the readout circuit is increased.Since the pixel circuit is very simple and this structure can eliminate the influence of column bus parasitic capacitance,it is very suitable for large-format small-pixel readout circuit.An experimental 128×128 DCA chip has been designed with 1.2-μm DPDM n-well CMOS technology.The charge handling capacity is 11.2pC with pixel size 50×50μm 2.A description of the readout circuit structure,pixel circuit,detector model,operation principle and chip layout is given in detail.Both excellent simulation results and experimental results of the fabricated DCA readout chip are presented.