Effect of drift region resistance on temperature characteristics of RF power LDMOS transistors

In this work, we investigated the effects of drift region resistance on the temperature behaviors of RF power LDMOS transistors. Devices with various implant doses in the drift region were fabricated. Owing to the quasi-saturation effect, the transconductances at high gate voltages are less dependent on the temperature for low-drift-dose device. In addition, the maximum oscillation frequency exhibits different temperature coefficients for devices with different drift doses. We derived an expression of unilateral power gain with 4th-order frequency term, and found that the drift resistance has a large influence on the device temperature characteristics at high frequencies.