To promote the modeling standardization process of the integrated circuits,an improved electrical simulation model for a direct power injection (DPI) setup which was used to measure the conducted immunity of a 16-bit microcontroller to radio frequency aggression was investigated.Based on the existing model of the same microcontroller,the PDN module was modified by adding the core,PLL and A/D network models,which could reflect the actual electric distribution situation within the microcontroller more accurately.By comparing the simulation results with the measurement results,the effectiveness of the modified model can be improved to 500 MHz,and its uncertainty is within +1.8 dB (±2 dB is acceptable).Then,to improve the simulation accuracy of the complete model in the high frequency range,the I/O model which contained the dynamic and nonlinear characteristics reflecting the variation of the internal impedance of the microcontroller with increasing the frequency of the external noise was introduced.By comparing the simulation results with the measurement results,the effectiveness of the second modified model can be improved up to 1.4 GHz with the uncertainty of +1.8 dB.Thus,a conclusion can be reached that the proposed model can be applied to a much wider frequency range with a smaller uncertainty than the latest model of the similar type.Furthermore,associated with the electromagnetic emission testing platform model,the PDN module can also be used to predict the electromagnetic conducted and radiated emission characteristics.This modeling method can also be applied to other integrated circuits,which is very helpful to the standardization of the IC electromagnetic compatibility (EMC) modeling process.