Showing papers on "Channel length modulation published in 1972"

Field effect semiconductor device having an unsaturated triode vacuum tube characteristi

Abstract: A field effect transistor comprises a semiconductor channel, a source and a drain electrode formed at the opposite ends of the channel and a gate electrode provided on the side of the channel. The channel has a small impurity density and therefore the depletion layer extending from the gate goes deep into the channel to substantially close the conductive portion of the channel even in the absence of a gate voltage. The drain current will not flow where the drain voltage is below a certain threshold voltage, and will flow where the drain volage is above the threshold voltage exhibiting a linear resistance characteristic. This drain-current to drain-voltage characteristic simulates the anode-current to anode-voltage characteristic of the triode vacuum tube very closely.

Current Saturation Mechanisms in Junction Field-Effect Transistors*

Abstract: Publisher Summary This chapter examines the current saturation mechanisms in junction field-effect transistors (JFET). A JFET is an active semiconductor triode in which the current is primarily carried by the majority carriers. An n -channel JFET consists of a lightly doped n -type channel sandwiched between two heavily doped p -type gate layers. The drain current flows parallel to the metallurgical gate junctions that are reversely biased. The reverse bias across the p-n junctions depletes free carriers from the channel and produces space-charge regions extending into the channel. Under the current saturation condition, the electric field along the channel near the drain is comparable to the field normal to the channel. This two-dimensional field distribution violates the gradual channel approximation that assumes negligible electric field along the direction of the channel. The finite channel model provides a path for current flow after saturation that avoids the difficulty in the depleted channel model. The chapter also states that space-charge-limited current is physically realizable in very short JFET structures that produce triode-like characteristics.