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Thurairaj M. Das M.B. Ballingall J.M. Ho P. Chao P.C. Kao M.-Y. 《Electron Device Letters, IEEE》1991,12(8):410-412
Experimental data are presented on equivalent gate noise voltage from 1 to 105 Hz obtained from lattice-matched and strained InGaAs quantum-well modulation-doped field effect transistors (MODFETs). In both types of devices excess generation-recombination (g-r) noise is observed at or below 100 Hz above an `apparent' background 1/f noise with spectral intensity ranging from 0.5×10-17 to 2×10-17 V2-Hz-1-cm2 at 1 Hz. These results are comparable to those reported by S.M.J. Liu et al. (1986) for the pseudomorphic MODFETs 相似文献
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A practical method to evaluate the parasitic source and drain series resistances of modulation-doped FETs is presented. The method is based on a modified gate-probe technique that uses the gate current crowding phenomenon. It is suitable for complex heterostructure devices since the carrier transport mechanism and physical structure properties around the gate region need not conform to ideal models 相似文献
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This paper analyzes the effects of the separation between the gate and the drain electrodes on the high-frequency performance limitations of heterostructure MODFET's. Based on the effective gate-length and carrier velocity saturation concepts first the key small-signal equivalent network model parameters of the MODFET are calculated. The concept of open-circuit voltage gain, defined as the transconductance to output conductance ratio (gm/go), has been exploited to determine the output conductance with a knowledge of the static electric field and potential at the edge of the gate on the drain side. By treating the coμn product as a function of the gate voltage, the drain current-voltage and transconductance characteristics have been effectively modeled for practical devices. By combining the effects of the intrinsic and parasitic equivalent network parameters this paper has determined the dependence of the gm/go ratio, the gate capacitance to the feedback capacitance ratio, the unity current gain frequency (fr) and the maximum frequency of oscillations (f max) on the gate-to-drain separation (Lgd). MODFET's based on InAlAs/InGaAs heterostructures lattice-matched to InP substrate with gate-length values of 0.25 μm, 0.15 μm and 0.1 μm are considered for analyses. The optimum values of Lgd calculated are 600 Å, 420 Å, and 340 Å for the corresponding maximum fmax-values of 250, 370, and 480 GHz, respectively 相似文献
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