Dual-gate multiple-quantum-well (MQW) heterojunction field-effect transistors (HFETs) for active phase shifters
✍ Scribed by Muhammad Nawaz; Geir U. Jensen
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 660 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0895-2477
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✦ Synopsis
We present a theoretical evaluation of the potential of dual-gate GaAs / AlGaAs multiple-quantum-well heterojunction field effect transistors (MQWFETS) 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 dualgate MQWHFET mostly depends on variation of the gate source capacitances CP,, Cgsz and the transconductance gmo2 with gate bias rather than on other intrinsic elements. Limited gate-bias ranges in the active regions of the deuice 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 deuice, 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 va ying different geometrical and structural parameters that influence the phase-shift and the gain characteristics. The use of different gate length gives a pat gain in the active regions. Using the same layer structure with different recess depths under the two gates results in a greater phase shift.