A thru-reflect-line calibration for measuring the characteristics of high power LDMOS transistors

摘要

The impedance and output power measurements of LDMOS transistors are always a problem due to their low impedance and lead widths. An improved thru-reflect-line (TRL) calibration algorithm for measuring the characteristics of L-band high power LDMOS transistors is presented. According to the TRL algorithm, the individual two-port S parameters of each fixture half can be obtained. By de-embedding these S parameters of the test fixture, an accurate calibration can be made. The improved TRL calibration algorithm is successfully utilized to measure the characteristics of an L-band LDMOS transistor with a 90 mm gate width. The impedance of the transistor is obtained, and output power at 1 dB compression point can reach as much as 109.4 W at 1.2 GHz, achieving 1.2 W/mm power density. From the results, it is seen that the presented TRL calibration algorithm works well.