Injection Efficiency of Direct Injection Mode Optical Sensors
直接注入模式可见光和红外传感器的注入效率

There are several kinds of solid state imaing sensors such as visible CCDs, IRCCDs, CMOS and infrared focal plane arrays (IRFPA). Their basic injection mode is that the signal is transported directly from a photodiode to a transition area via an injection channel. The research and development of direct injection techniques over the past 30 years are summarized. The theory and basic formulas of the direct injection mode of visible and infrared imaging sensors are analyzed. The result shows that the increase of the transconductance of an input gate and the impedance of a photodiode is the most effective method to improve injection efficiency when the sampling frequency is low. The transconductance of an input gate can become infinite by using a new current mirroring direct injection circuit when the impedance of a photodiode is low, and hence the injection efficiency can be close to 100%. The new circuit design method is analyzed. A direct injection circuit with a 64-element InSb linear array is developed. The preliminary test indicates that its injection efficiency is close to that of the theoretic analysis.