PHEMT saturation velocity and mobility is taken 1.5 ϫ 10 7 cm/sec and 7000 cm 2 /V ⅐ sec, respectively. CONCLUSIONAn analytical noise modeling is performed using an accurate charge-control model to evaluate the small-signal parameters and noise properties of HEMT and PHEMT. This model shows improved behavior of transconductance and gate-to-source capacitance near the threshold region; hence, the calculated curves of minimum noise figure F min and minimum noise temperature T min show good matching with the experimental data. Excellent agreement with the experimental results ensures the validity of the proposed model. The effects of gate length and donor layer thickness upon noise performance are also studied, which suggest that noise performance improves with reducing gate length and increasing thickness, however, one needs to maintain the aspect ratio in order to avoid short-channel effects. ACKNOWLEDGMENTThe

One means of converting the port conditions of a magic-tee into those of a 908 hybrid is to introduce external sections of waveguide at the symmetrical H-plane output ports having the necessary 908 phase difference. The purpose of this article is to describe a number of realizations of such differential phase shifters (DPS), including an exact synthesis procedure not requiring computer optimization. A typical design consists of a capacitively loaded waveguide for one section and an essentially inductive waveguide for the other. The latter is simply a uniform waveguide of reduced width when compared with that of the capacitive section. An example capacitive ridge DPS exhibits a maximum phase error of 628 over a 20% bandwidth in WR75 waveguide with a return loss of better than 40 dB and an insertion loss <0.06 dB.

EVWUDFW ²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² 3ODQDU FLUFXLWV /RZ SDVV ILOWHUV 6SOLW ULQJV UHVRQDWRUV &RPSOHPHQWDU\ VSOLW ULQJ UHVRQDWRUV &655V

No abstract

No abstract