CASFET: A MOSFET-JFET cascode device with ultralow gate capacitance

A field-effect transistor is described that combines a short-gate MOSFET with a long-channel JFET in a cascode configuration. The composite device, a CASFET, can have a very low input capacitance due to the short gate of the MOSFET combined with the reduced Miller capacitance of the cascode. The long channel of the JFET insures that the CASFET has high output resistance. This paper discusses CASFET fabrication, performance, and modeling.