Compact Modeling of LDMOS Transistors *

Abstract

The semiconductor revolution which started in the 1960s has led to tremendous developments in the area of device design. One point to note is that LDMOS devices are restricted to a niche of high-voltage and low-current circuits, such as cellular telephony, analog power management, "smart" power applications, and automotive and audio electronics. When the gate bias exceeds the threshold voltage of the device, an inversion channel is created, and the carriers flow toward the lightly doped drift region. One of the most distinguishing features of LDMOS devices is the presence of the quasi-saturation effect in the output characteristics. The input characteristics of the device are along expected lines—that is, the threshold voltage kept increasing as the temperature decreased. This is the first compact LDMOS model capable of operating at deep cryogenic temperatures and replicating impurity freeze-out behavior. Since the LDMOS temperature behavior is non-monotonic, greater accuracy can be achieved by using four or more temperature points.