In this study ,we designed an infrared focalplane array (IRFPA) digitalreadout integrated circuit (ROIC) for medium/long-wave (MW/LW) dual-color applications. Owing to the variation in the magnitude of the injection current ,dynamic output impedance of dual-color IRFPA devices ,and the high sensitivity required for both bands ,the structural design of two inputstages and a large dynamic range must be achieved within the limited pixel area of the ROIC. Therefore ,the proposed circuit adopted a pulse frequency modulation (PFM) structure based on a directinjection (DI) type inputstage and a charge resetunitto replace the traditional voltage reset structure ,reducing the detectable charge resolution and improved the nonlinear effect caused bytheresetlostcharge. We designed a20-bithybrid structurecounterto satisfythe large-charge capacity and low-power consumption requirements of the circuit. Simulation results demonstrated thatthe minimum chargeresolution was692e- ,corresponding to a chargecapacity of0. 72Ge. The dual-band detection linearity exceeded 99. 8% ,and the power consumption was 3. 03/6. 66μW in typicalMW/LW applications.