Parameter Extraction and Comparison of Self-Heating Models for Power MOSFETs Based on Transient Current Measurements

A self-heating parameter extraction method for a circuit simulation model is discussed based on the transient drain current measurement, by using an 18-V LDMOS as a test device. Important quantities for self-heating models, self-heating-free drain current, thermal resistance R_th, and thermal capacitance C_th are directly and simultaneously extracted from the transient current measurements. The method is efficient in improving the fitting quality in the short-time domain after switching and in guaranteeing the consistency among the extracted quantities. Based on the method, two kinds of thermal network are compared and discussed for the on-wafer measurement. It is demonstrated that the 1R1C model using the method carries fitting errors only in the narrow range of time and that the fitting errors can be removed only by adding one pair of thermal resistance and thermal capacitance which represent the thermal distribution below the device.