Characterization of RF lateral-diffused metal-oxide-semiconductor field-effect transistors with different layout structures

Abstract

The DC and RF characteristics of lateral-diffused metal-oxide-semi conductor (LDMOS) transistors with different layout structures were studied. The devices were fabricated using a 0.5 mu m LDMOS process. The ring and fishbone structures, which are used widely in power devices, were designed and analyzed. We found that the. transconductance, on-resistance, cutoff frequency and maximum oscillation frequency were improved using the ring structure, due to a larger equivalent W/L and lower drain parasitic resistance. In addition, the self-heating effect of LDMOS transistors was also investigated by measuring the pulsed current-voltage (I-V) and pulsed RF characteristics. From the measured results, the ring structure appeared to be a better layout design for RF LDMOS transistors.