Title :
Improved small-signal equivalent circuit model and large-signal state equations for the MOSFET/MODFET wave equation
Author :
Roblin, Patrick ; Kang, Sung Choon ; Liou, Wan-Rone
Author_Institution :
Dept. of Electr. Eng., Ohio State Univ., Columbus, OH, USA
fDate :
8/1/1991 12:00:00 AM
Abstract :
A simple non-quasi-static small-signal equivalent circuit model is derived for the ideal MOSFET wave equation under the gradual channel approximation. This equivalent circuit represents each Y-parameter by its DC small-signal value shunted by a (trans) capacitor in series with a charging (trans) resistor. A large-signal model for the intrinsic MOSFET is derived by first implementing this RC topology in the time domain. Modified state equations are then introduced to enforce charge conservation. Transient simulations with this approximate large-signal model yield results that are compared with reported exact numerical analysis for the long channel MOSFET for a wide range of bias conditions. This unified small- and large-signal model applies to both the three- and four-terminal intrinsic MOSFET in the region of the channel where the gradual channel approximation is applicable. A non-quasi-static small-signal equivalent circuit for the velocity-saturated MOSFET wave equation is also reported
Keywords :
equivalent circuits; high electron mobility transistors; insulated gate field effect transistors; semiconductor device models; MODFET; MOSFET wave equation; RC topology; Y-parameter; charge conservation; four-terminal intrinsic MOSFET; gradual channel approximation; intrinsic MOSFET; large-signal model; large-signal state equations; long channel MOSFET; nonquasistatic equivalent circuit model; range of bias conditions; small-signal equivalent circuit model; state equations; three terminal MOSFET; time domain; transient simulation; unified small/large signal model; velocity-saturated MOSFET wave equation; Capacitors; Cutoff frequency; Dielectric constant; Electrons; Equivalent circuits; MODFET circuits; MOSFET circuits; Partial differential equations; Resistors; Voltage;
Journal_Title :
Electron Devices, IEEE Transactions on
