Research On IP Library Based On Macro Model Of Microbolometer

Microbolometer type uncooled infrared focal plane array(IRFPA) is a typical monolithic integrated micro-electromechanical system(MEMS). Microbolometer has suspended bridge-like structure which integrated with the read out integrated circuit(ROIC) on the same wafer by MEMS technology. At this stage, microbolometer and ROIC cannot be designed and simulated in the same design platform. The design of microbolometer always starts with finite element method(FEM) tools, while ROIC is designed in circuit simulation tools, which means there is no link between bridge-like structure and ROIC designing. It is difficult to establish a system-level design methodology, and the overall performance of IRFPA cannot be evaluated accurately. So it results in a long design cycle, high cost and restricting the rapid development of microbolometer. Thus, this paper focuses on establishing the connection between the design of microbolometer and circuit, as well as achieving system-level simulation.Equivalent circuit macro model of microbolometer is established by using thermal analysis and electrical analysis. Macro model is described by Verilog-A hardware language and then the basal IP library of microbolometer is established in circuit simulator Cadence Virtuoso. Thermal capacity, thermal response time, thermal conduction, initial resistance and temperature coefficient of resistance are extracted by FEM and theoretical calculation. In order to verify the basal IP library, the parameters which mentioned above are added in IP library and analyzing the output characteristics of IP library in Spectre. The results match the theoretical expectations well which demonstrates the microbolometer IP library could present the characteristic of the microbolometer. It provided a possibility for microbolometer to accomplish system-level design.The device and ROIC can be designed in the same platform by calling the basal IP library of microbolometer in IC simulation environment, and then the system-level design can be achieved. This system-level design method of microbolometer offered a fast way to simulate, a credible way to make sure the range of manufacturing, and an efficient way to design.