Research On Read-out Circuit For Uncooled Infrared Sensor

Uncooled infrared sensor has been the research hotspot in the field of infrared thermal imaging and has a wide range of applications in the commercial, military, civil and other fields. Among them, the diode-based infrared sensor takes the PN junction as the temperature-sensitive unit, and is easily compatible with standard CMOS process.After the flow process, the infrared sensor needs to complete the post-CMOS fabrication and release the suspended structure of the diode pixel through dry etching and TMAH wet etching. In this paper, the fabrication process of the diode-based infrared sensor has been investigated. Meanwhile, a structure of smaller pixels in series has been designed. Changing the pixel structure of diode-based infrared sensor and making the small P+/N well units in series, the sensitivity of the sensor is improved in infrared radiation. The structure designed is proved to be able to enhance the strength and sensitivity of the output signal by the simulation and experiment, solving the problem of weak output effectively and meeting the needs of the actual test. Meanwhile, a MOS transistor circuit is designed to get further amplification.As the output voltage of the infrared sensor is week, the read-out circuit has to be designed to read the output signal. According to the characteristics of the infrared sensor'signal, the read-out circuit has been designed, including the constant current source module, the amplifier module and filtering module. The output signal of infrared sensor under the heat source is measured through the simulation and experiment. In addition, an infrared sensor data acquisition system is set up, using the FPGA development board and the ADC chip.The research on the fabrication and read-out circuit for infrared sensor can provide the basis for the study of infrared focal plane, which is also favorable to the study of the Infrared Imaging technology.