To un-cooled infrared focal plane arrays ( un-cooled IRFPA) based on sensitive resistance, it has been proved that integral technique can improve the signal-to-noise of the detector in the CMOS readout integrated circuits.The design scheme of RO IC with an array of 160 ×128 has been presented, the circuitwith temperature compensation and design of the integrator have been introduced. The simulation result of the control timing of the resistance-selec-ting and integrator are given at last. The results show the scheme can be app lied to CMOS RO IC with a larger array such as 160 ×128 and 320 ×240.