Abstract A variable resistance field effect transistor with a wide range of resistance and a linear ohmic characteristic having one or more small channels and one or more large channels formed by a gate region between a source region and a drain region in which both the small and large channels are located closer to the source electrode than to the drain electrode. The field effect transistor is such that as the gate voltage is changed from full drain current flow to pinch-off, the small channels are pinched off at first, after which the large channel or channels will reach a pinch-off voltage. In depletion type field effect transistors, with zero voltage on the gate electrode, the entire current through all of the small channels is much larger than the total current flowing through the large channels. The small channels may be of different size, since even if one channel is pinched off at a certain gate voltage, the next larger channel is not pinched off at that voltage. In another embodiment, the gate region is such that the channel area is gradually increased so that the pinch-off voltage is also gradually changed in accordance with the size of the channel.
A field effect transistor comprising a body of semiconductor material of a first conductive type, a first planar layer of semiconductor material of a second conductive type formed with a plurality of windows of varying sizes and with the larger window formed in a central portion of said first layer and said windows becoming progressively smaller from the central portion, said first layer of semiconductor material mounted on one surface of said body of semiconductor material and portions of said body of semiconductor material extending through said windows and flush with the surface of said first layer away from said body of semiconductor material, a second planar layer of a first conductive type mounted on said first planar layer and covering said windows but not covering outer portions of said first planar layer, a planar source electrode of electrical conductive material formed on said second planar layer, a planar drain electrode of electrical conductive material formed on a second surface of said body of semiconductor material which is opposite to said one surface, and a planar gate electrode of electrical conductive material formed on said outer portions of said first planar layer.
Claim 2
Dependent Claim
192 words
A field effect transistor comprising a body of semiconductor material of a first conductive type, a first planar layer of semiconductor material of a second conductive type formed with a plurality of windows of varying sizes and with the larger window formed in a central portion of said first layer and said windows becoming progressively smaller from the central portion, said first layer of semiconductor material mounted on one surface of said body of semiconductor material and portions of said body of semiconductor material extending through said windows and flush with the surface of said first layer away from said body of semiconductor material, a second planar layer of a first conductive type mounted on said first planar layer and covering said windows but not covering outer portions of said first planar layer, a planar source electrode of electrical conductive material formed on said second planar layer, a planar drain electrode of electrical conductive material formed on a second surface of said body of semiconductor material which is opposite to said one surface, and a planar gate electrode of electrical conductive material formed on said outer portions of said first planar layer.
Claim 3
Dependent Claim
25 words
A field effect transistor according to claim 1 wherein said body of semiconductor material is n type and said first planar type is p type.
Claim 4
Dependent Claim
16 words
A field effect transistor according to claim 2 wherein said second planar layer is n+ type.
Claim 5
Dependent Claim
30 words
A field effect transistor according to claim 1 wherein said first planar area comprises a large central window and a plurality of smaller windows arranged about said large central window.
Claim 6
Dependent Claim
24 words
A field effect transistor according to claim 4 wherein said plurality of smaller windows are crescent shaped concentrically mounted about said large central window.