Intermodulation distortion behavior in LDMOS transistor amplifiers

An analysis of the intermodulation distortion (IMD) behavior of LDMOS transistor amplifiers is presented. It is shown that the turn-on region abruptness compared to most other devices is important for explaining the measured IMD behavior such as sweet-spots. The analysis is validated using two-tone measurements at low frequency for different classes of operation. A 1.9 GHz LDMOS power amplifier is designed and characterized to investigate the IMD behavior also at higher frequency.