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ABSTRACT: Sub-nanosecond impulse response of high-voltage InGaAs/GaAs HBTs was characterized by using a time-domain sampling oscilloscope with the cable delay and loss corrected in frequency domain. A peak voltage of 10 V with a width of 200 ps was obtained, which was attributed to the delayed onset of the Kirk effect. The Agilent HBT model was modified to account for the stronger-than-expected field and temperature dependence of the Kirk effect. The modified model correctly predicts the impulse response of the HBT and, hence, can be used in the design and simulation of impulse-based ultra-wideband circuits.
Microwave Symposium, 2007. IEEE/MTT-S International; 07/2007
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ABSTRACT: A new large signal HBT model is proposed and experimentally evaluated, which contains measurement based diffusion charge and analytical depletion capacitance formulations. In order to account for the complicated dependency of diffusion charge on bias, transit times at various bias points are extracted from measured data and contour-integrated. Using spline functions in the interpolation of transit times, modeled RF characteristics are continuous and smooth up to 3rd order derivative with respect to collector current in the wide range of bias. Base-emitter depletion capacitance C<sub>be</sub> is implemented considering GaAs emitter capping layer as well as InGaP emitter layer. It is shown that the new formulations of diffusion charge and depletion capacitor improves the accuracy of the large-signal model. Simulation results are verified with comparison to measured S-parameter and gain characteristics in the whole bias range.
Microwave Symposium Digest, 2005 IEEE MTT-S International; 07/2005
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ABSTRACT: Reliability tests for production level 6 inch InGaP HBTs have been investigated. 6 inch InGaP HBTs have been fabricated and qualified in terms of etching and DC/RF performance uniformity before the reliability test issues. A three temperature accelerated test has been performed to predict MTTF at a certain temperature using the Arrhenius expression. The extrapolated MTTF at a junction temperature 125°C is 1.5×10<sup>8</sup> hours with an activation energy of 1.98 eV. Furthermore, humidity stress tests were also carried out.
GaAs Reliability Workshop, 2002. Proceedings; 11/2002
