Readout integrated circuit (Roic) should be applied with clock work pulses which are usually generated by signal generator, discrete component, MCU and complex programmable logic device (CPLD). In this paper, a method of designing clock work pulses with CPLD for linear infrared focal plane array (FPA) capacitance trans-impedance amplifier (CTIA) readout integrated circuit is presented. Experimental results show that this circuit can be capable of driving FPA steadily after overshoot of work pulse is eliminated by increasing series-resistance at the output terminal. This portable circuit with small volume can be used for FPA’s reliability test. Comparision result of experimental value and design value shows that this circuit is not suitable for parameter measurement because of low resolution compared with high-precision signal generator.