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Dual‐gate multiple‐quantum‐well (MQW) heterojunction field‐effect transistors (HFETs) for active phase shifters
Author(s) -
Nawaz Muhammad,
Jensen Geir U.
Publication year - 1996
Publication title -
microwave and optical technology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.304
H-Index - 76
eISSN - 1098-2760
pISSN - 0895-2477
DOI - 10.1002/(sici)1098-2760(19960820)12:6<322::aid-mop6>3.0.co;2-h
Subject(s) - transconductance , optoelectronics , transistor , materials science , heterojunction , phase (matter) , field effect transistor , active layer , physics , electrical engineering , engineering , layer (electronics) , nanotechnology , voltage , quantum mechanics , thin film transistor
We present a theoretical evaluation of the potential of dual‐gate GaAs/AlGaAs multiple‐quantum‐well heterojunction field effect transistors (MQWHFETs) for active phase shifters in the frequency range 4–60 GHz. The computer‐aided design program TOUCHSTONE was used to study the phase‐shift characteristics. The transmission phase of a dual‐gate MQWHFET mostly depends on variation of the gate source capacitances C gs1 , C gs2 and the transconductance g mo2 with gate bias rather than on other intrinsic elements. Limited gate‐bias ranges in the active regions of the device operation result in a quasi‐linear phase shift for analog applications. For digital applications, a maximum differential phase shift of 36, 51, 63, and 105 degrees at f = 12, 20, 30, and 60 GHz, respectively, was obtained by switching both control gate biases discretely. Compared to a single‐gate device, a dual‐gate MQWHFET shows an increase in differential phase shift by 9–90% from 12–60 GHz. Furthermore, a dual‐gate device provides extra possibilities by varying different geometrical and structural parameters that influence the phase‐shift and the gain characteristics. The use of different gate lengths gives a flat gain in the active regions. Using the same layer structure with different recess depths under the two gates results in a greater phase shift. © 1996 John Wiley & Sons, Inc.